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HIGH-SPEED STEEL 



Published by the 

McGraw-Hill BookCompany 

New 'York. 

(Successors to tke Book. Departments of tke 

McGraw Publishing Company Hill Publishing" Company 

Publishers of Books for 
Electrical World The Engineering - and Mining Journal 

The Engineering Record rbwer and The Engineer 

Electric Railway Journal American Machinist 



Characteristic Colors 
(in full daylight) 



Pale Yellow 

Stra 

Dark Straw 

Brown Yellow 

Light Purple 

Purple-blue 

Full Blue 

Polish Blue 

Dark Blue 



DEGREES 



Bright Red 
in the Dark 



Red in Twilight 



Nascent Red — * 



Red- 



Dark Red 



Cherry 

Bright Cherry 

Dull Orange - 

Light Orange - 

Lemon 

Light Straw 

White 
Brilliant White 

Dazzling White 




Characteristic 
Phenomena 



— ^ Softening Begins 

Range of Ar 
> (Softening Critical 
I Points) in Carbon 

Steel 

Softeuing Completed 



^Softening Begins 



j Range of Ar 
•s in High Speed 
Steel 



Softening Completed 

>> [Range of Arj.Ar.,, 

Xand Ar, in Carbon 

ISteel 



Nascent Cherry — »- 5 - === 800 IT [Range of Ar,,Ar, 

1500 = — N and Ar, inHigh- 



^| [speed Steel 
(heating) 



> Hardening Range 
High-speed Steel 



Frontispiece 

Heating Phenomena, Fahrenheit and Centigrade Scales. 



HIGH-SPEED STEEL 



THE DEVELOPMENT, NATURE, TREATMENT, AND USE 

OF HIGH-SPEED STEELS, TOGETHER WITH SOME 

SUGGESTIONS AS TO THE PROBLEMS 

INVOLVED IN THEIR USE 



BY 

O. M. BECKER 

INDUSTRIAL ENGINEER 



McGRAW-HILL BOOK COMPANY 

239 WEST 39th STREET, NEW YORK 

6 BOUVERIE ST., LONDON, E. C. 

1910 



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$> 



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Copyright, 1910, 

BY THE 

McGRAW-HILL BOOK COMPANY 



Stanhope iptcsa 

F. H. GILSON COMPANY 
BOSTON, U.S.A. 

©CU2689H7 



INTRODUCTION 



It is rather unusual that any considerable time should elapse between 
the announcement of a great discovery and the appearance of a book deal- 
ing specifically and comprehensively with the subject of that discovery; and 
especially is this true when the idea or invention has such a far-reaching, 
even revolutionary, influence in its particular department of the world's 
activities as is the case with high-speed steels. Nevertheless during the 
decade and more since Fred W. Taylor and Maunsel White unexpectedly 
stumbled upon the high-heat treatment for tungsten and related steels, 
and developed their high-speed steel, nothing has been published which 
could be called at all adequate as a treatment of the subject, except pos- 
sibly Mr. Taylor's address before the American Society of Mechanical En- 
gineers on the occasion of his inauguration as president, at the December, 
1906, meeting; and the articles hereafter mentioned. This address or 
report is indeed a monumental work, including as it does the results of his 
experiences and researches, and those of his co-laborers, in the carrying 
on of his investigations. These researches, it would seem, have been more 
extensive and thorough than any others yet attempted, covering the gen- 
eral subject of the new steels. Other investigations, covering limited 
portions of the field, like those of Dr. H. C. H. Carpenter, say, have 
been exhaustive as far as they extended, and also are very valuable for the 
light they throw upon the nature and the possibilities of high-speed steel. 

The Taylor report confines itself largely to the experiences of its author 
and his associates, and unfortunately, has not a good index. There has 
been a pretty general feeling for some time that a work should be available 
which would cover comprehensively the whole subject of high-speed steels, 
presenting in an understandable way a general view of it in such form as 
to be easily accessible for reference. This was in the mind of the present 
writer when he was invited some five years ago to contribute to the 
Engineering Magazine a series of papers dealing with the subject. The 
articles were written and printed, 1 and, as far as appears, formed the most 
extensive account of the new steels, as adaptable to use in productive 
industry, which had been published up to that time. 

1 Engineering Magazine, New York and London. Issues of September, October, 
November, and December, 1905 ; May, June, and August, 1906. 



iv INTRODUCTION 

Since the original articles - appeared much new light has been thrown 
upon certain aspects of the subject. Mr. Taylor's address has been pub- 
lished, and many sporadic contributions of greater or less value have ap- 
peared in the technical periodicals. Furthermore, important developments 
have been worked out concerning which little or nothing at all has been 
heretofore printed. While therefore this book is in a sense based upon 
the series of articles already mentioned, it is by no means the same. Such 
of the original material as has proved fundamental has been retained and 
brought into accord with present knowledge and practice. Much has been 
added touching the historical and theoretical aspects of high-speed and 
other tool steels. The purpose has been to include all that might be of 
interest in connection with the subject and to present an accurate con- 
spectus of the present state of knowledge concerning the new steels. 

The entire subject is so recent, however, and astonishing developments 
have followed one another with such bewildering rapidity, that the accom- 
plishing of this purpose presented many difficulties. Almost every steel man 
knows the practical impossibility of obtaining detailed information concern- 
ing tool steels which is absolutely accurate and reliable. The personal 
equation and a multitude of other factors commonly accounted negligible, 
so much affect results that the assertion might be safely hazarded that all 
conclusions as to method and means in steel treatment are subject to 
allowances for these elements. Thus, for illustration, two different plants 
operated by the same concern make large use of the barium process in 
hardening. At one the temperature commonly maintained and' indicated 
by the pyrometer is 1200 degrees C. (2200 F.), while at the other an 
instrument of the same make and calibrated with equal care uniformly 
indicates only 1070 degrees C. (1950 F.); and yet as far as can be seen by 
the eye of an experienced operator, familiar with both plants, the two 
baths are kept at identical temperatures. Certain it is that results equally 
good are obtained at both plants. 

Similar difficulties arise in connection with methods and apparatus. 
Thus, it is maintained with much fervor by some that the only furnace 
giving good results is coke-fired; while others insist with equal fervor that 
oil or gas fired furnaces alone can be depended upon. Similarly, con- 
clusions as to superiority of one or another brand of steel over others are 
almost uniformly based on insufficient grounds or arrived at under condi- 
tions not precisely duplicated (or not likely to be duplicated) elsewhere. 

Great care has been taken to insure absolute accuracy of statement, and 
definiteness in every respect. The reader must remember, however, that 
in view of the considerations just set forth, there may be some disagreement 
with methods here proposed and conclusions presented. The endeavor 
has been not only to cover, in the chapters dealing with the practical han- 
dling of the new steels, all points likely to come up, and to indicate clearly 
just what is believed to be best practice at the present time; but, where 



INTRODUCTION V 

there is diversity of opinion, to describe all practical methods shown to 
yield satisfactory results. 

In conclusion the author wishes to express his appreciation of the assist- 
ance rendered by Mr. Walter Brown and Mr. D. G. Clark. Except for 
their encouragement and patient assistance during the early days of the 
work the task, if undertaken at all, might never have been finished. Grate- 
ful acknowledgment is also made of the interest manifested and assistance 
rendered in the ways of suggestions, criticism, permission to use material, 
and proof reading by Mr. Fred W. Taylor, Dr. H. C. H. Carpenter, Mr. 
George H. Paltridge, Dr. Bradley Stoughton, and others. Dr. Carpenter 
was especially helpful with suggestions in connection with the chapter on 
the Nature and Characteristics of the New Steels; and Dr. Stoughton was 
kind enough to revise portions of the same. Acknowledgment for the use 
of illustrations is made in the appropriate places. 

O. M. BECKER. 

Chicago, III., 
July 1, 1910. 



CONTENTS 



Page 
Introduction 

Section I. The Development and Nature of High-Speed Steels. 

Early Tool Steels 1 

Self-Hardening and High-Speed Steels . . . 13 

Nature and Characteristics of the New Steels 22 

Still Newer Steels 49 

Section II. Making the Steels and Tools. 

Process of Making High-Speed Steel 55 

Forging the Tools 64 

Hardening — The High Treatment Practically Applied 78 

Hardening — The Barium Chloride Process 105 

Tempering 121 

Annealing 129 

Grinding 134 

Ascertaining and Regulating Temperatures 155 

Miscellaneous Observations on the Making of High-Speed Tools 178 

Section III. The Tool at Work. 

Range of Utility of High-Speed Steel 186 

Conditions of Maximum Effect 212 

Speeds and Feeds, and Related Matters 235 

Section IV. The New Requirements. 

Fundamental Considerations in the Design of the New Tools 252 

The New Machine Requirements 275 

Remodeling an Old Equipment 295 

Section V. Problems Involved in the Use of High-Speed Steels. 

Statement of the Problem 300 

Making a Beginning 319 

Section VI. Appendices. 

A. Analyses of High-Speed and Special Steels 330 

B. Taylor on Hardening High-Speed Tools 332 

C. Reference Table for Determining Cutting Speeds 334 

D. Diagram for Determination of Time of Turning Operations 336 

E. Summary of Metal Removed and Cost of Removal 338 

F. Taylor Tables of Practicable Speeds 339 

Index 345 



HIGH-SPEED STEEL. 



CHAPTER I. 



THE DEVELOPMENT AND NATURE OF HIGH-SPEED STEELS. 

EARLY TOOL STEELS. 

The Earliest Tools. — That the extraction of iron from its ores was 
practiced long before historical times, is evidenced by many remains 
of prehistoric forges and smelters. Not a few implements of that 
material whose antiquity cannot be doubted, also have been found. 
Scriptural authority ascribes the first forging of iron to Tubal Cain, 
whose time "is generally fixed at about 38 centuries B. C. Whether or 
not steel dates back so far as that, it is quite certain that steel imple- 
ments must have been used not much later, in the construction of certain 
of the very earliest ancient monuments known to us; for tools of soft 
iron could not have cut and carved the very hard rocks of which they. 
were constructed. In connection with the building of the pyramids 




Fig. 1. The monumental carvings of Egypt are conclusive evidence that the ancient Egyptians 
possessed good steel tools, which alone could have cut the hard stones smoothly. The pictures 
themselves sometimes, as in this case, indicate the kind of tools in use and the methods of 
using them. 

(date fixed at about three thousand B.C.) Herodotus speaks of the 
immense sums of money which. must have been spent for the " iron " 
with which the builders worked; and in the Great Pyramid there was 
found a fragment of an iron tool which must be at least five thousand 
years old, containing a small percentage of carbon. There is good 
reason for believing also that the working of steel as well as of iron was 
known to and practiced by the early Greeks and others, perhaps as far 
back as ten centuries B. C. 

Ancient Steel Making. — As to the method making of the common 
steels of antiquity, little is certainly known. The iron to be converted 
into steel appears to have been made in a sort of crude Catalan forge; 
and as iron has a strong affinity for carbon, it is probable that in forg- 
ing iron which had been long in contact with the fuel and therefore 

1 



2 HIGH-SPEED STEEL 

had taken up some carbon, it would be found somewhat harder and 
stiffer than common iron, and on that account more suitable for tools. 
Among the very ancient Egyptians, it is said, pieces of meteoric iron 
were heated in close contact with the fuel and kept at a high tempera- 
ture, just below the melting point, for a long time. The absorption of 
carbon was of course sufficient to make a superior iron, or steel, of the 
piece so treated. The next step in the development of steel no doubt 
was the accidental dropping into water of a red-hot tool of some kind. 
The superior hardness and usefulness of such a tool would certainly 
lead to further experiment and more careful treatment. Whether or 
not this was the actual course of events in the development of ordinary 
steel, it is certain the ancients possessed some remarkably good steel 
implements and knew pretty well how to use them. 

The ancient method of working metals was by forging, chiefly. If 
this did not give a suitable result, or if a sharp cutting edge was required, 
recourse was had to abrasives. Machinery being practically unknown, 
it was impossible for primitive men to do much in the way of metal 
cutting, although indeed it seems that graving or hand cutting of some 
kind was practised almost if not quite as far back as the time of Tubal 
Cain. Certain it is that the art was practiced among the Chinese long 
before the Christian era began. 

Ancient Metal Cutting. — Not however until the beginning of what 
has aptly been called the age of machinery, which dates' back scarcely 




Permission of The Iron and Steel Magazine. 

Fig. 2. A primitive furnace for smelting iron and producing steel. The ore and fuel lie in the fore- 
ground. In charging the furnace, these were carried up the rude steps carved in the hillside against 
which the furnace was erected. 

more than a century, did the real development of metal cutting begin. 
A crude form of the lathe had been known for a good many centuries, as 
long ago indeed as the days of Solon, in the sixth century B. C; but 



THE DEVELOPMENT OF HIGH-SPEED STEELS 3 

this improved but little upon the tedious and laborious hand-cutting 
process. The arrival of steam power made possible the development 
of relatively heavy and powerful machinery, and permitted the large 
development of cutting tools. 

Wootz, Damascus and Toledo. — From the earliest times the quality 
of steels varied greatly. The celebrated wootz steels of India, and 
Damascus made at the Syrian city of the same name, and later at Toledo, 
in Spain, were examples of superior steels susceptible of extraordinary 
tempering. They both, however, were crucible steels, and the latter 
is also said to have contained strong traces of tungsten, nickel, man- 
ganese, and similar elements important in the new high-speed steels. 

Production of Wootz. — Wootz is a steel of high quality, the manu- 
facture of which reaches back to very ancient times. Aristotle, the 




Fig. 3. Section of a crude Catalan forge, still to be seen in remote places, in which steel is often made 
directly from the ore. The charcoal and ore, the latter in small lumps, are charged at the level of 
the floor or a little above. As the reduction proceeds, a more or less steely lump, the "loupe," 
collects at the bottom. 

Greek philosopher, describes it as nearly as 350 B. C. or thereabouts, 
and tells us how it was made. Other ancient writers in the subse- 
quent centuries likewise make mention of it. This steel still is (or 
at any rate until recently was) fabricated by some of the remote 
mountain peoples in the north of India. The method of manufacture 
is essentially the same as that described by Aristotle nearly twenty- 
three centuries ago. First the iron is extracted from the ore in a sort 
of rude clay Catalan forge, perhaps built against the side of a hill. The 
result is a lump of sponge iron, which is hammered to make it more 
dense and to rid it of as much of the unmelted ore and cinder as may 
be. The lump is then broken into smaller pieces, hammered again, 



4 HIGH-SPEED STEEL 

and afterwards placed in a specially prepared small clay crucible, holding 
about a pound of metal. Along with the iron is put some finely divided 
wood, and a few green leaves, the latter laid at the top of the charge. 
The crucibles are luted up and placed in a diminutive furnace of clay, 
generally a bare two feet in diameter, conical, and sometimes partly 
below the surface of the ground. The blast is furnished by a pair of 
skins blowing through a bamboo and clay tuyere. 

After several hours the crucible is tested for complete fusion of its 
contents, by being shaken; and if the melting is complete, the crucible 
is allowed to cool, to be later broken open. The result, if successful, 
is a small lump of exceedingly fine, smooth-surfaced steel, which takes 
a remarkable temper. This steel has been used almost exclusively 
for swords as far back as tradition runs; and it has been said of Wootz 
blades, as also of Damascus, that when properly tempered and skill- 
fully handled they would cleave a bar of iron without losing edge. It 
has been declared also that a blade of wootz has cleanly cut a wisp of 
silk floss tossed into the air. 

Crucible Steel among the Chinese. — This product of ancient skill 
seems to have been little if at all known, as an article of commerce, to those 
nations who have done most toward the advancement of civilization 
through the development of the steel and iron-making art. Nor, 
apparently, was it known to them that steel was produced in eastern 
Asia contemporaneously with, and as now seems established, long 
before wootz was made in India. Recent archaeological discoveries 
indicate that a kind of crucible steel was known to and made by the 
Chinese probably many centuries before the Indian product. The 
method by which the Chinese steel was produced is not yet known. It 
probably was something like that practiced in India; the more so since 
there are indications that both these peoples may have learned the 
process from a common source, a people living in the plateau between 
the two lands. 

Manufacture and Nature of Damascus. — Damascus steel likewise was 
a crucible steel. It differed from wootz however, and from other 
steels as well, in one respect. Those familiar with its appearance are 
aware of the curious veining or figuring seen on the surface. This 
characteristic, adding greatly to the beauty of a finished surface, is 
due to thin strips of soft iron alternating with similar strips of steel, 
and these thoroughly welded, twisted and otherwise completely wrought 
together. This steel was first made, as far as known, at the ancient 
Syrian city (said to be the oldest existing city in the world) whence it 
derives its name, and doubtless also is of great antiquity. The Scrip- 
tural reference to " iron from the north," together with other allusions 
in Scripture and the historical references to the Chalybes (whence is 
derived the Greek and Latin names for steel) indicate that the region 



THE DEVELOPMENT OF HIGH-SPEED STEELS O 

north of Damascus, if not that city itself, was a renowned center for 
steel manufacture hundreds of years before the beginning of the Chris- 
tian era. 

Virtues of Ancient Steels. — The virtues of Damascus steel were made 
famous throughout the western world by the crusaders, and its manu- 
facture was at a later period established at Toledo, in Spain. Toledo 
blades came to have a repute almost as great as those made at Damas- 
cus. It is stated that they possessed tempering qualities as remarkable 
as those of wootz, and that they were sometimes packed in boxes curled 
up like clock springs of our day. 

Whether or not these ancient steels possessed all the remarkable 
qualities attributed to them, they certainly were marvels of their time; 
and indeed they remain marvels in our own time. Nothing superior 
to them, in respect of tempering quality, has been produced by modern 
methods of steel making. It is certain that all of the steels mentioned 
were at some time or other used for tools of various sorts, very likely 
for use in the metal-cutting arts. For the latter purpose, however, 
they possessed no striking advantage over other steels. 

Variability of Primitive Steels. — The quality of ancient steels, and 
of those produced up to a comparatively recent time, varied greatly. 
Considering the methods of manufacture and the diversity of ores 
used, this is not surprising. Some ores would contain elements wanting 
in others; and in the process of forging, or perhaps of extraction, certain 
tools would be in closer and longer contact with the fuel and would 
therefore absorb more carbon. Modern manufacturing methods make 
it possible to eliminate all these uncertainties, and it is comparatively 
easy to produce continuously steel of practically constant quality. 

Development of Metal Cutting. — The development of metal cutting 
was, until a few years ago, brought about almost wholly through the 
evolution of the machine by which the tool was made to do its work, 
and scarcely at all through the development of excellence in the tool 
itself, except in so far as it was found that varying shapes gave varying 
results. The steel, its nature, and the method of treatment, remained 
much the same as for centuries before. 

With the development of powerful machinery, however, it was soon 
found that there was a limit to the amount of work to be got from a 
tool for cutting metal. The tenacity with which the particles of a 
homogeneous mass of steel, iron, or similar tough metal cohere makes 
it no slight matter to drive a tool into the mass or force off a portion 
of it. A small graver in the hand can easily make a scratch in the 
surface of an iron plate; but to remove a chip say a quarter of an 
inch by three-quarters, a cut by no means unusual nowadays, involves 
the consumption of an astonishing amount of power. Now the energy 
used up in making a cut, is partly, of course/converted into latent energy 



6 HIGHSPEED STEEL 

stored in the chip with its changed form and changed relation of con- 
stituent particles; and partly into sensible heat at and near the cutting 
point of the tool, which heat is taken up by the tool, the chip, and the 
piece being machined. The chip being relatively small and continu- 
ously changing in respect to the particles of metal at the cutting point, 
rarely gets so hot as to show a color higher than deep blue, and not 
often that. The piece machined is relatively large, and readily absorbs 
and conducts away its portion of the heat, which is a small part only 
of that generated. The tool, however, is continuously at work, and 
absorbs a good deal of the heat generated. Now if the tool be worked 
heavily, which is to say usually if the cutting speed be relatively high, 
the cutting edge quickly gets so hot as to draw the temper and make 
the ordinary carbon steel tool useless. 

Endurance Limit of Tools. — Evidently there is a limit to the amount 
of work such a tool is capable of doing; and this limit, the snail's pace 
at which it has heretofore been necessary to carry on metal-cutting 
operations, has been an anomaly in modern industry the chief character- 
istics of which are magnitude and speed. There is a vim and vigor 
about wood-working operations as seen in a modern shop, which is 
exhilarating. A large spindle, for example, is shaped while revolving 
at the rate of two or three thousand turns per minute, the rate, of course, 
depending somewhat upon the size and nature oj: the wood. A steel 
shaft of similar diameter revolving against an ordinary tool at a very small 
fraction of the same number of turns would almost instantly " burn " it. 

Maximum Speed with Carbon Tools. — Carbon steel, as heretofore 
used in tools, no matter how well hardened, has not enough toughness 
and hardness to withstand the rubbing of the chip for any considerable 
length of time, even when not run fast enough to affect the temper. 
The tool therefore dulls; and this dulling proceeds in a sort of geomet- 
rical ratio as the cutting speed increases, being augmented by the draw- 
ing of the temper which accompanies rapid cutting. The speed in all 
metal-cutting operations has therefore had to be comparatively 'slow, 
no matter how powerful might be the machines in use. Thirty feet 
of chip per minute, as any machinist knows, has been considered rather 
good work; while fifty feet per minute has been very unusual. Under 
ordinary circumstances the management of a shop was pretty well 
satisfied if the machine tools could maintain an average speed of twenty 
to twenty- five feet per minute. 

Such deliberation, necessary though it has been, is depressing in 
this era. A creeping mass of metal turning leisurely round and round 
or moving back and forth, as has been customary in the average shop, 
is quite out of harmony with the modern spirit of expedition and hurry. 
But while a few dreamed of the possibilities of cutting metal, some 
time in the future, with something of the vim with which wood can be 



THE DEVELOPMENT OF HIGHSPEED STEELS 7 

cut; and while machines had been developed so tremendously as to 
leave scarcely anything to be desired in that respect; nevertheless the 
ultimate limit seemed to have been reached. 

But it had not. 

Similarity of Ancient and Modern Steels. — For at least a thousand years, 
and probably for several thousand, there had been no single important 
advance, no one striking development, in the nature and characteristics 
of steel, in respect to metal-cutting qualities at any rate. The property 
of becoming hard, possessed in common by all steels, and distinguishing 
them from ordinary iron, is due to the presence of carbon diffused 
throughout the mass of the metal. How the presence of the particles of 
carbon brings about the virtue of hardening is yet a matter of discussion. 

The Modern Science of Steel Making. — Modern steel making is a fact 
only because the science of chemistry, itself scarcely a century and a 
half old, has made it possible to understand that there is an affinity 
of certain elements for certain others and that under given conditions 
exactly the same combinations can be expected in chemical compounds 
and alloys. , The prehistoric steel makers had no idea that in firing 
iron with certain fuels they were carbonizing it, actually forming of 
the iron and fuel a new substance which contained besides iron the same 
element which in one form constitutes charcoal, in another graphite, 
and in a third, diamond. That, however, is exactly what they did. 

Blister and Double Steel. — The method of the very ancient steel 
makers, except as already noted, was essentially the same as that com- 
monly in use up to comparatively modern times. The bar to be car- 
bonized was heated in close contact with charcoal or other suitable 
fuel. In later times this was done in a sort of double muffle furnace, 
and the cementation or carbonization was more even and complete. 
Steels thus made however, were found to be only skin deep, so to speak; 
for since trie carbon merely soaked in and combined with the iron nearest 
to it, evidently the central portion was less completely carbonized than 
the exterior, and except possibly in very thin bars was generally quite 
devoid of the hardening element, even after ten or twelve days' treat- 
ment. In later times, when the muffle furnace came into use, steel 
thus made was known as blister steel, from the blisters or scales appear- 
ing on its surface during the process of carbonization. This steel is 
not dense and uniform enough for fine tools. It was known for many 
centuries, however, that hammering (and later rolling) so as to " work " 
it thoroughly, greatly improved the quality and usefulness for tool 
making of such " cementation " steels. An improvement upon this 
method was that of breaking the bars into lengths, bundling them, and 
then welding together. The " shear steel " thus produced was of much 
better texture and uniformity, but was not so good as the " double " 
or " double shear " steel which was made by repeating the process a 



8 HIGHSPEED STEEL 

second time. Damascus seems to have been made somewhat in this 
fashion, but after the desired uniformity had been obtained in the steel 
itself, thin layers of the steel and of fine iron seem to have been again 
welded together. The grainy or " watered " appearance of Damascus 
is said to be due to this streaking with iron. 

Revival of the Crucible Method. — " Shear " or " double " steel was 
of course a great deal better adapted to edge tools than any produced 
by the earlier methods; but it still had the disadvantage of being more 
or less streaked and spotted, for no amount of hammering or rolling 
could entirely eliminate the inequalities of carbonization by the cemen- 
tation process. It was not until about the middle of the eighteenth 
century that a method of overcoming this defect was discovered. About 
that time one, Huntsman, was astonishing other makers of blister steel 
by the absolutely uniform texture of his steel. It lacked the " seams " 
or streaks characteristic of the other steels of that day, and hardened 
uniformly all the way through. Keeping a process or method secret 
was at that time considered the only way of distancing competitors, 
and Huntsman and his workmen managed to keep their trade secret to 
themselves until the envy of a competitor, so the story runs, imposed 
upon their humanity and learned the secret. On pretense of seeking 
shelter one stormy night this competitor, according to the tradition, 
appeared at the forge where the wonderful steel was made, and was at 
last admitted for humanity's sake. What his expectant but astonished 
eyes beheld was so absurdly simple that he may well have wondered 
why he and others had not thought of it also. It was in fact nothing 
but the melting of the broken pieces of blister steel in a crucible. Of 
course the steel made in such a way would be uniform, for each crucible, 
at any rate. Had the spy but known it, however, he beheld a process 
which in its essential features was centuries old; for as the reader has 
already seen, crucible steel has been known in some parts of the world 
since time immemorial. 

Later Methods. — Steel made by Huntsman's method came to be 
known as " crucible " or " cast " steel. The first name is still considered 
a sort of trade-mark for steel made in this way, though there are many 
other steels nowadays made in pots or crucibles and in one sense there- 
fore entitled to be so called. This crucible steel at once came into favor 
and held its position as the tool steel par excellence until the introduc- 
tion of mushet steel and the subsequent development of the Taylor- 
White process. The result of these advances was something essentially 
different and in every way superior for most, if not indeed for all, tools 
used in the metal-cutting arts, and perhaps also for all cutting pur- 
poses. The only important change in manufacturing crucible steel was 
made by the elder Mushet about the beginning of the last century. 
Instead of melting blister steel in the crucible, he used refined iron 



THE DEVELOPMENT OF HIGH-SPEED STEELS 9 

(scrap or bar) mixed with some carbonaceous compound. The soft 
iron was thus carbonized in about the same way as the sponge iron in 
making wootz. Steel produced in this -way, however, had not the ex- 
cellence of that made in India; nor even of the blister-crucible steel of 
Huntsman. Some fairly good steel is thus made, but usually it needs 
to be thoroughly " worked " to make it dense and good enough for fine 
tools. Later Mushet mixed pig-iron with the contents of the crucible; 
and this is still usually clone except when the blister-crucible steel is 
required. 

A peculiarity of crucible steel is that it must be " dead-melted " or 
else it is liable to be more or less porous and otherwise imperfect. This 
consists merely in allowing the melted steel to remain fluid in the crucible 
for a half hour or more, before pouring. 

Open Hearth Steel. — Many attempts have been made to produce as 
good a steel by other methods, whereby the cementation process could 




Fig. 4. Longitudinal section through a Siemens regenerative open hearth furnace. To start the fur- 
nace a wood fire is burned in the two chambers at one end of the furnace (G and A). When these 
are red hot, a current of air is passed through the brick checkerwork in A, and up a flue to M; a 
current of fuel gas is passed through the checkerwork in G, and up a flue to TV. The gas and air, 
thus preheated, meet at K and fill the furnace chamber with a hot flame, which radiates its heat to 
the metal on the hearth H. The hot gases then pass down to chambers A and G on the opposite 
end of the furnace, and store their waste heat in the brick checkerwork there. At intervals of 15 
to 20 minutes, the currents of air and gas are reversed in direction, and enter the furnace through 
the alternate pair of regenerative chambers, taking from them the stored-up heat to create a still 
more intense flame over the hearth. 



be avoided. There have been, and still are, many forms of open hearth 
furnaces which produce a fair quality of steel direct from pig or from 
refined iron; and the bessemer process has been greatly improved and 
modified in so far as results are concerned. But neither of these type 
processes produces a satisfactory tool steel, though some very good 
results have been secured from certain carefully made open-hearth steels. 



10 



HIGH-SPEED STEEL 



In the open hearth furnace (Fig. 4) from five to nearly one hun- 
dred tons of steel can be made at a heat, whereas the crucible process 
makes but fifty to one hundred pounds per pot. Essentially the open 
hearth process consists in remelting old steel scrap and mixing with it 
pig iron, which is either melted at the same time or else brought in the 
still liquid condition from the blast furnace in which it is made. The 
proportion of pig iron will vary all the way from ten to nearly one hun- 
dred per cent, depending on the state of the market, the quality of steel 
to be made, and other like conditions. Pig iron is an impure iron con- 
taining three to four per cent of carbon, one to two per cent or more 
of silicon, sometimes phosphorus, manganese and other impurities. 
The impurities are diluted by the mixture of steel scrap, and are further 
reduced through oxidation by iron ores added to the furnace charge 
for the purpose. When the bath is purified to the desired point, man- 
ganese and a little silicon are added to rid it of dissolved oxygen. 

Open hearth steel is used in immense quantities in machinery and 
structural work, but makes tools inferior to those of crucible steel. 1 The 
heats are large, which necessitates pouring them into large-sized ingots, 
and these are softer and inferior in the center after cooling. The man- 
ganese added to cure the superoxidation is not a perfect antidote, and 
it is impossible to prevent imperfections in steel made in this way, or 
to obtain such a uniformity of hardness as is required for the best tools. 

Bessemer Steel. — In the Bessemer process, liquid pig iron is brought 
from the blast furnace and poured into the converter (see Fig. 5), The 




Fig. 5. Section of a bessemer converter. Silicon, manganese and carbon are removed from the molten 
pig iron by blowing air through it. The converter is mounted on trunnions, T, one of which is so made 
that a blast of air passes through it and along a duct, D, to the bottom, whence it comes up through 
openings, A, in the bottom. When the metal is judged to be in proper condition, the converter is 
rotated on the trunnions and the charge emptied. 



1 That is, inferior to crucible steel made in the manner described, for steels have 
been put upon the market under that name which are quite inferior. Though possibly 
they have been melted in a crucible, the name is misleading, and usually is intended 
to be so. 



THE DEVELOPMENT OF HIGH-SPEED STEELS 



11 



carbon and silicon in the metal are then Burned out by blowing a spray 
of cold air bubbles through the molten bath. This combustion supplies 
the heat which not only keeps the metal liquid, but even raises its tem- 
perature some hundreds of degrees, and white hot flame pours from the 




Fig. 6. The bessemer converter in action. 



mouth of the converter during the ten minutes or so while the purifi- 
cation proceeds. After practically all of the carbon and silicon are 
removed, the predetermined dose of melted iron rich in carbon, man- 
ganese and silicon (known as the " recarburizer ") is poured into the 
converter to rid the metal of superoxidation and give it the desired grade 
of carbon, and it is then cast into ingots. 

Bessemer steel is still more liable to irregularities and imperfections 
than open hearth, and is unsuitable for good grades of tool steels. 



ft 



HIGH-SPEED STEEL 



Electric Steel. — The production of steel in the electric furnace is the 
only other important process in use today, and by this means electrical 
energy is substituted for fuel in producing the necessary heat. The 
metal is entirely protected from oxidation in this process and is capable 
of a purification unattainable by any of the others. The steel is said 
to be superior even to crucible steel, and to be made at a less cost. 



CHAPTER II. 

SELF-HARDENING 1 AND HIGH-SPEED STEELS. 

Manganese-Bessemer. — The addition of manganese to the contents of 
the bessemer converter made it possible to work the steel freely while 
hot and helped give bessemer steel its well known properties. It was 
Robert F. Mushet, himself interested in steel manufacture, who sug- 
gested the addition of manganese in the making of bessemer. He 
did not stop with the results his suggestion quickly brought about, 
but continued making experiments for the improvement of ordinary 
steels. He had at this time no idea of improving steels for use in tools, 
particularly; but was working primarily to get the best possible steel 
for ordinary use. While carrying on these experiments, however, he 
made a discovery of far-reaching importance to all those industries in 
which metal cutting is practiced. 

He discovered self-hardening steel. 

Discovery of Mushet Steel. — Ordinary steel, owing its hardening 
property to the presence of carbon, has been hardened from time im- 
memorial by quenching in water while at a red heat, as is well known. 
If allowed to cool slowly, as in the air, it is too soft for use in tools. 
During the course of his experiments, sometime in 1868, Mushet found 
that one of his bars seemed to have the property of becoming hard 
after heating, without the usual quenching. This circumstance was 
not merely singular; it was astonishing, and contrary to all previous 
experience. Possibly it marked a new epoch in steel making. Analysis 
of the bar behaving so singularly showed that it contained a percentage 
of tungsten. 

Properties of Tungsten Steels. — Not only did the bar containing 
tungsten harden without the customary quenching, but it was actually 
harder than ordinary steel which had been quenched. It occurred to 
Mushet that this extraordinary circumstance might be turned to advan- 
tage in the production of superior tool steel, and he accordingly set him- 
self to developing tungsten steel with this end in view. The result of 
experimenting with hundreds of metal mixtures in the crucible was a 

1 Mushet steels soon came to be known in England as "self-hardening." After a 
time the term "air-hardening" was used more or less in the United States along with 
"self-hardening." In this book the term "self-hardening" will be used to refer to 
mushet steel, though of course high-speed steels also are partially self-hard. On the 
continent high-speed steels are frequently known as "rapid steels." 

13 



14 HIGH-SPEED STEEL 

steel alloy much more satisfactory than any other then in use, which 
possessed the property of becoming very hard by mere exposure to 
the air. 

Improvements in Air-Quenching Steels. — It was not until after the 
steel had come into somewhat general use that it was discovered by 
Mr. Henry Gladwin, then associated with Mr. Mushet at the Clyde 
Steel Works, Sheffield; and by several other engineers almost at the 
same time, that still better results could be obtained if the cutting 
portion were reheated and then cooled in an air blast. This discovery, 
in Mr. Gladwin's case, at any rate, was the result of laying some bars 
of mushet steel on the earth floor of a smithy, near the door. A draft 
swept over the cooling bars, and they were later found to be superior 
to bars cooled where there was no draft. Later experiments showed 
that cooling in an air blast was still better; and that further improve- 
ment in the quality of tools could be made by bringing the color to a 
full scaling or almost yellow heat during the re-heating. This, however, 
was not usually done by toolsmiths, and in consequence most users 
failed to work mushet tools at their highest efficiency. 

Mushet Steel in Engineering. — The new steel was immediately put 
upon the market under the name " R. Mushet's Special Steel." The 
company organized for its manufacture, and sale, however, did not 
succeed well in business; and some three years later the production of 
mushet steel was taken over by Samuel Osborn & Co., Ltd., at the 
Clyde Works, Sheffield. The wide introduction of the new steel into 
engineering works, and its imitation under the name of air- or self- 
hardening steel quickly followed. 

A substantial advance had been made in the art of cutting metals. 
It was possible to turn and plane (at first the use of mushet steel was 
limited to these operations) at double or triple the former speeds; and 
to machine pieces formerly quite too hard for the tools available or so 
hard as to make the cost of operation prohibitive. Even after their 
general use in engineering works, mushet tools were but little used for 
increasing speeds — most usually only to save frequent grindings or 
to permit doing jobs previously impossible. 

It was not until a full quarter century after mushet or self-hardening 
steel had become an established fact in engineering that the marvelous, 
and in the light of all previous experience paradoxical, properties latent 
in it were clearly appreciated, and the industrial world caught a glimpse 
of what promised to be a revolution in machine shop methods. 

The Taylor- White Investigations. — The discovery of the possibilities 
in tungsten steel, like that of the nature of the steel itself, was for- 
tuitous, if indeed not accidental. In both cases the circumstances 
that led to the discovery were quite undesigned, and the discovery 
merely incidental to something else. As far back as 1894 Mr. Fred W. 



SELF-HARDENING AND HIGH-SPEED STEELS 15 

Taylor began experimenting with mushet and other self-hardening 
steels with a view to determining which was best suited to special kinds 
of work. This was but a single feature of his program of improving 
shop efficiency and of determining a logical system of shop management. 
Shortly after taking charge of the Bethlehem works in 1898 he associated 
with himself Mr. Maunsel White and others, for better prosecuting the 
work in hand. After careful tests had been carried on for a time it 
was decided that a certain make of steel, with proper heating in the 
tempering process, could be run at higher speed than any of the others; 
and it was thereupon decided to adopt this make for exclusive use in 
the shops. , 

In order to demonstrate their superior efficiency to all the foremen 
and thus be sure of hearty co-operation in making a change of so great 
magnitude as was involved in changing a large proportion of the tools 
then in use, a number of tools of various kinds of steel were ordered 
carefully dressed, tempered, and ground to exactly the same shape. 
The foremen were then assembled to witness the comparative perform- 
ances of the tools. To the astonishment, and we may well believe 
chagrin, of the demonstrators, the tools made of the selected steel failed 
to make a good showing. In fact they proved to be inferior to any 
others in the lot. That is, they could not be worked at as high a speed. 

Very naturally so unexpected a circumstance would arouse the curi- 
osity and interest of such keen investigators as were Taylor and White. 
It had to be accounted for; and so another investigation was set on foot. 

The range of heating, in the case of carbon steel tools, as is well under- 
stood, is rather narrow. Air-hardening steels have a still narrower 
but higher range; and the excellence of a tool depends upon the care 
exercised in heating it to just the necessary temperature when " draw- 
ing " or tempering. The first thought that occurred to Taylor and 
his assistants naturally was that the heat treatment of the tools which 
failed had been faulty; that very likely they had been under-heated. 
Whether this was so, or not, seems not to have been definitely deter- 
mined. One thing however, was determined; namely, that a series of 
experiments should be undertaken to find out just what would be the 
effects of various degrees of heating, ranging all the way from a black 
to temperatures considerably beyond what had been previously thought 
permissible. 

The High Heat Treatment. — The results of the experiments were star- 
tling indeed. When the investigators were in the midst of the work laid 
out, it was realized that they had made a discovery which upset all 
previous beliefs as to the effects of heat upon steel, and which was 
apparently bound to bring about ultimately a revolution in machine 
shop practice. It was nothing less, indeed, than that steels of the 
tungsten class instead of being ruined by high heats, were actually 



16 



HIGH-SPEED STEEL 



improved so greatly that cutting speeds became possible which pre- 
viously had been only dreamed of; the discovery, in fact, of the high- 
speed qualities inherent in these alloy steels when subjected to the 
super heat treatment. 

Nothing surprising was noticed until tools were heated considerably 
higher than had been customary, so high indeed that in the light of all 
experience the treatment was ruinous. Tools thus superheated were 
not ruined, but on the contrary stood up to their work better than those 
given the usual treatment; and apparently the higher the heat treat- 
ment, the better the tool. For unnumbered centuries it had been 
believed that steel must not be heated beyond a red; but here were 
tools which not only were not ruined, but which got better the higher 
they were heated. The heating, it was found, could actually be carried 
up to the melting point; and a tool so treated would cut more metal 
and do it more rapidly than one not raised to so high a temperature. 

The deterioration of tools which had been heated to near 875 degrees 
C. (1600 F.) was not surprising; for it was previously well understood 





































































CD 

a, 
to 

00 

g 

s 



























































































800 825 850 875 900 925 950 975 1000 1025 1050 

Degiees Cent. 
Fig. 7. Curve showing the influence of the high heat treatment on tungsten steels. 

that all steels were damaged by being heated so high as this — though 
indeed, Mushet recommended heating his air-hardening steel to a full 
scaling or almost yellow heat, which is not far from 1200 degrees C. 
(2200 F.). This deterioration is shown in Figure 7, which indicates the 
relative cutting speed possible with mushet steel when heated to tem- 
peratures varying from 800 to 1050 degrees C. (1450 to 1900 F.). The 
surprise came when the tools were heated to beyond 925 degrees 
C. (1700 F.), for with each very slight increase of temperature used 
in hardening, the cutting power was increased to an extraordinary 
extent. 

Improving Air-Hardening Steel. — Tools of this sort were not, however, 
wholly satisfactory. The cut was rough, and it was by no means cer- 
tain that the alloy used was the best for this sort of treatment. The 



SELF-HARDENING AND HIGH-SPEED STEELS 17 

discoverers, not satisfied with the results already attained, began to inves- 
tigate the effect of varying the proportions of the alloy and of the intro- 
duction of other elements. The outcome of a large number of trial 
mixtures was a steel capable of doing from three to six times as much 
work as had previously been possible, and which required for the develop- 
ment of its greatest efficiency a heat treatment which would utterly 
ruin ordinary steels. 

True, it has been pointed out that tungsten and other hardening 
elements besides carbon were present in some steels of very ancient 
manufacture, and the tungsten-chromium-manganese steels with which 
these experiments were carried on had been known for some years. 
The method of high-heat treatment nevertheless was certainly new, 
though it would seem that the Mushet experiments and recommended 
practice, if they did not quite anticipate the Taylor discoveries, ap- 
proached very close to them. Even if it had been known, the combina- 
tions of alloys in the ancient steels referred to were quite incapable of 
developing the powers which modern high-speed steels acquire through 
the high-heat process, and the old mushet steels needed modifying and 
improving to adapt them in .the highest degree to the new method of 
treatment. 

Rivalry in Experimentation. — For some time the discoverers managed 
to keep their process to themselves and to the shops to which they sold 
the rights; but a discovery of such far-reaching importance was bound 
to become known. Indeed they had no intention of keeping it secret 
except as a means whereby they might be enabled to carry on further 
investigations. As soon as the nature of the new steel and the processes 
of treating them became generally known to the technical and engineer- 
ing world, and the possibilities of high-speed cutting were in some degree 
apprehended, manufacturers of tool steel on both continents at once 
began to vie with one another in their efforts still further to perfect the 
tungsten steels and to enlarge the range of their usefulness. In the 
aggregate an immense amount of money has been spent in experimenta- 
tion with a great variety of mixtures and methods of manufacture. 
One manufacturer alone tried over two hundred different mixtures and 
another worked some four years before the product was thought satis- 
factory. Others have no doubt carried on experiments on a scale 
equally large, and possibly larger. At the time of this writing (1909) 
there are perhaps a hundred different brands of high-speed steel upon 
the market, and new brands of the so-called "new," " improved," or 
" superior " high-speed steels are multiplying at a rate which bids fair 
to double the number within a short time. 

Faults of Early High-Speed Steels. — The first high-speed steels, 
though of astonishing cutting and wearing qualities, were not adapted 
to finishing and other fine work. Their coarse, granular structure, 



18 HIGHSPEED STEEL 

perhaps, did not take a cutting edge such as would leave a good finish; 
and so the new tools were used mostly for coarse and heavy work. 
This defect has been, in some if not in all brands, completely overcome; 
and high-speed tools are now in use not only for the finest grades of 
metal cutting, but for wood cutting, which certainly is an extreme test 
of the smoothness of a cutting edge. It may be thought strange that 
high-speed steel should be used in a wood shop, where speeds have for 
a long time been as high as is expedient and safe. There is no particular 
gain in speed in wood cutting. The advantage in putting high-speed 
steel tools to this use lies almost wholly in their superior wearing quality. 
The immediate first cost usually is greater, but the life is incomparably 
longer, while the cost of maintenance is trifling. This of course is 
important where many such tools are used. 

Marvels of the New Tools. — The thing in the way of running ordinary 
tools at high speed when working on metals has already been shown 
to be the overheating of the tool near the cutting edge, and the con- 
sequent drawing of its temper, which is of course quickly followed by 
the rubbing away of the edge and the ruin of the tool. This series of 
steps follows as a result of the friction of the chip bending and sliding 
over the tool. The high-speed steels (are not, within certain limits, 
thus affected. Indeed, they seem almost to require abuse in order to 
bring out their highest capabilities. It is a common experience in shops 
that tools of these steels will not work to the best advantage until they 
have been run a little while and " warmed up." The speed capabilities 
and cutting power of these tools are indeed marvelous, compared with 
former experience. Thirty feet of chip per minute is a good performance 
with carbon tools; and the average on such work is not likely to be 
much over twenty, in a well-regulated shop. A hundred feet per minute 
has been mentioned as the extreme record of carbon-steel tools; and 
under ordinary conditions rarely is it possible to attain fifty feet con- 
tinuously. But high-speed tools in more than one shop cut a hundred 
and fifty feet and more as a regular performance, and higher speeds 
still are not at all unusual. Though this is several times as fast as was 
formerly possible, and is perhaps about twice the average in ordinary 
shop practice with the new tools, it is by no means the limit. It has 
been demonstrated that such tools can be worked up to more than three 
hundred feet per minute; and it is claimed that a speed of four hundred 
feet has been maintained continuously in cutting carbon steel with a 
comparatively small cut {\ inch) and a slight feed. Mr. J. M. Gledhill, 
a well-known authority on the subject, has asserted (Proceedings of the 
Iron and Steel Institute, New York meeting, October, 1904) that five 
hundred feet is attainable. 

At the Paris exposition of 1900, where high-speed tools were first 
publicly demonstrated, there was shown a lathe tool working for con- 



SELF-HARDENING AND HIGH-SPEED STEELS 19 

siderable periods at a speed so great that the nose of the tool was red 
much of the time. In present regular practice tools are not permitted 
to get red hot, for softening to some degree inevitably takes place 
and the edge does not hold up. The chips as well as the tools of course 
get hot; and the former often come off with a deep-blue color when cut 
at a very high speed. 

The Chip Problem. — The removal of steel chips, when coming off so 
fast, is in itself a problem. In one test the services of two laborers were 
required to keep the machine clear. The total amount of metal removed 
in the case of some very large machines built with the purpose of utiliz- 
ing the new tools to their limit, is prodigious. Obviously there is nothing 
but disadvantage in removing metal unnecessarily; but there are cases 
where heavy cuts are unavoidable, and even economical. Under these 
circumstances it is not uncommon for cuttings to be removed at the 
rate of two thousand pounds per hour. Nor is this by any means the 
limit. There are recorded tests where double this rate has been at- 
tained for short periods. In actual everyday practice it is not unusual 
for a tool to cut several hundred pounds of chips per day, and that too 
without having to be ground more than once or twice. 

Inadequacy of Old Machine Types. — The pressure exerted in taking 
heavy cuts and the power required to drive machines at the high speed 
demanded by the new tools are tremendous. In a test, already men- 
tioned, the stress upon the tool was in excess of one hundred tons. To 
resist such forces'and to hold the tool and work firmly in proper relation, 
ordinary machines are quite inadequate. Machines a few years ago 
considered paragons of efficiency are, since the advent of the new steels, 
able to utilize but a fraction of the total efficiency of the tool; and while 
there is usually considerable advantage in the use of the new tools, it 
is only by using extremely heavy and rigid machines of the newer type 
that the full advantage is to be secured. 

Revolution in Machine Shop Practice. — Revolutions do not occur 
in a day, especially in the industrial world. There have been great indus- 
trial changes, several of them indeed, within the hundred and some years 
since handiwork ceased to be the chief agency in production. But 
these changes have been rather in the nature of evolutions. A new 
discovery or method gradually made itself necessary, and after a time 
there was a new order of things in which the former methods, once the 
standard of efficiency, became antiquated and had to be abandoned. 
High-speed steel evidently is one of those discoveries which will eventu- 
ally bring about a new regime in the metal-working industries. And 
while there is small likelihood that things will be very quickly upset, 
the carbon-steel tool made obsolete and the machine of yesterday's 
design antiquated, it now appears certain that after a few years carbon- 
steel tools will have a small place anywhere. Even razors are now 



20 HIGH-SPEED STEEL 

sometimes made of high-speed steel and are said to hold an edge better 
than carbon steel. 

It is true that the new steels are as yet little known in many shops, 
especially the smaller ones, and that they are used very stingily in many 
large ones. The high cost seems to deter many from using them, and 
perhaps also in some cases the failure of first trials made without a satis- 
factory knowledge of how to make or use the new tools. Tungsten, 
molybdenum, and other like steel-hardening metals are rare, and con- 
sequently expensive, costing as high as $7 a pound in some cases. 
The manufacture of high-speed steel likewise is a more expensive pro- 
cess than that of making carbon steel. Of course for high-class tools 
crucible steel has been generally used; and crucible steel costs more 
to make than that produced by other processes. But even so, crucible 
steels sell as low as five cents, and occasionally even less, per pound; 
though the better grades, those most commonly used in tool making, 
sell anywhere from ten to twenty cents a pound, according to the grade; 
whereas ordinary high-speed steels sell for sixty to seventy-five cents 
per pound, and the " improved " steels run considerably higher in price. 

Efficiency of High-Speed Tools. — Eventually, no doubt, as processes 
are simplified, the cost will be much lower. Even at the present high 
cost, however, considering what it is capable of doing, high-speed steel 
is usually cheaper in the end. It has been a not uncommon experience 
that the cost of machine work on particular parts has been reduced 
one-half or more, though of course this could not be possible in many 
cases. If so, the industrial revolution in the metal trades undoubtedly 
would not only be at hand, but quickly accomplished. If the time 
required for cutting were all that entered into jobs of this sort, of course 
the cost reduction would be in proportion to the cutting speed. But 
every user of tools knows that often more time is required to get ready 
for a piece of work than for doing it. Frequently, indeed, the cutting 
time is an insignificant fraction of the total required; and obviously 
in such cases small economy of time could be expected. Nevertheless 
it is a rare case in which the tool-maintenance account is not capable 
of being reduced to a greater extent than the first cost is increased. 

Contrary to the general belief, the greatest saving effected by the use 
of high-speed steel ordinarily is not in the cutting of hard materials. 
The economy here is great, in general; but upon soft material it is prac- 
tically double what it is in the case of hard material. 

The Modern Way of Making Discoveries. — Many, perhaps most, of 
the important discoveries which have made civilization what it is were 
accidental, or at any rate not designed. Fortuity nowadays however 
plays a relatively unimportant part in discovery and invention. Even 
though an important idea be stumbled upon undesignedly, its perfection 
into a useful invention usually involves painstaking development. Men 



SELF-HARDENING AND HIGH-SPEED STEELS 21 

conceive problems and set themselves earnestly to their solution, calling 
to their aid all available previous experience and knowledge in science or 
whatever may have bearing upon the problem in hand. It does not 
follow that the problem is always satisfactorily solved. Likewise it not 
infrequently happens that an investigation started to get at one thing, 
eventuates in something else not closely related. At some point in the 
development there may be indications pointing to divergent or even very 
different lines of investigation, which if carried on intelligently lead to 
results possibly more important than those first sought. Something like 
this was the development of the high-heat treatment of tungsten steels. 

The problem to which Mr. Taylor had set himself some twenty years 
before his most important discovery, was the development of a rational 
system of shop management — one that would obtain the highest 
possible efficiency in men and machines. Naturally, good tools, the 
best that could be made, were essential to such a system; and experi- 
mentation along this collateral line came to be perhaps the most impor- 
tant of all. In the pursuit of these investigations and the development 
of high-speed steel a very large amount of money was spent, many 
mistakes were made, and infinite patience was exercised. Something 
like fifty thousand recorded tests were made besides a great number 
not recorded, and close to a million pounds of steel and iron were cut 
into chips, the total expense having been estimated as not far from 
$200,000. 

Since the tungsten steels and their peculiar treatment have become 
generally known to the industrial world, and others have undertaken 
to experiment with them, probably much more has been spent in their 
further development. And still high-speed steel is but in its infancy. 
Like other inventions, it will undergo a process of evolution, one so 
complete, let it be hoped, as to leave little to be desired in respect of 
its utility. There is undoubtedly still plenty of room for painstaking 
and patient investigation and experimentation. In spite of all which, 
however, high-speed steel has already had a marked influence upon 
production, so that no shop can be said to be up-to-date which ignores 
its possibilities. 



CHAPTER III. 

NATURE AND CHARACTERISTICS OF THE NEW STEELS. 

Alloy Steels. — Until comparatively recent times the name steel was 
given by general consent to such a combination of iron and carbon 
(as we now know), together usually with slight proportions of certain 
other substances, as possessed the qualities of high tensile strength, 
homogeneity, toughness, and ability to resist crumbling, and which 
when treated in a particular way became considerably hardened. Later 
the distinction between steel and some varieties of iron became so 
slight that now it is very difficult to v make a definition which will in- 
clude, even in the case of the carbon steels, all those iron alloys commonly 
designated steel, and which at the same time will exclude those of 
practically identical composition, thoiigh perhaps of different structure, 
which are admittedly not steel. It is, in fact, impossible to draw a 
sharp line between mild steel, produced in an open-hearth furnace, 
and iron made by the puddling or other process, except for the presence 
of slag in puddle iron. The latter not infrequently has a higher carbon 
content than the mild steel. Before the development of the modern 
processes, it was comparatively easy to decide whether a given sample 
was steel or iron. If it hardened on being quenched in water after 
having been heated to a good red, it was plainly steel. But mild steel, 
with its low content of carbon, does not harden any more than wrought 
iron does. With the advent of the newer steels still greater difficulties 
are in the way of a suitable and precise definition, and it would be 
hazardous to venture one here. It is sufficient for our purpose to take 
for granted that the name steel may properly be applied to any alloy 
of iron with carbon, or of iron and carbon in combination with other of 
the so-called hardening elements, which permits hardening and temper- 
ing in a way to combine a relatively high tensile strength, reluctance 
to fracture, and resistance to crumbling. 

Nomenclature. — Since the discovery that substances other than carbon 
in virtue of their presence give iron the quality of becoming hard and 
tough under certain treatment, or at any rate assist carbon in producing 
this result, it has become necessary to make distinctions between the 
various kinds of steels, and it is now customary to speak of them in a 
general way as carbon, mushet or air-hardening, and high-speed or 
rapid steels. Various other terms have been suggested, but have not 

22 



NATURE AND CHARACTERISTICS OF THE NEW STEELS 23 

come into general use, though the term "alloy steel is frequently used 
to designate all other steels than those depending upon carbon chiefly 
for their specific qualities. The alloy steels in turn are frequently 
designated as vanadium steel, tungsten steel, and the like, according 
to the distinguishing alloy; and because tungsten was the first and still 
is the most common of the elements used in the alloy steels, they are 
often spoken of as tungsten steels even though that element be in 
particular cases of minor importance or quite absent. The several 
alloy steels are used for various purposes to which their individual 
characteristics particularly fit them. Nickel steel, for instance, is 
largely used for armor plates and projectiles, and chrome and vanadium 
steels are largely used for the structural parts of machinery subjected 
to great strains, as in the case of certain automobile parts. It is 
not with this use of alloy steels, however, that we are at present 
concerned. 

Composition of Ordinary Steels. — Ordinary carbon steel, such as has 
through the ages been used for tools, contains small proportions of 
elements other than iron and carbon. Some of these are useful and 
perhaps even necessary to make the steel easily workable, either in 
forging or melting. This is the case of silicon and manganese. Both 
tend to make steel sound by preventing the formation of blowholes. 
Silicon, in the quantities usually present in tool steels, has small, if any, 
effect upon the tool; though in steels for some other purposes, where 
the proportion of silicon may be larger, it causes stiffness and possibly 
also adds to the hardness. When present in excess of say three or four 
per cent it causes brittleness and red shortness. Manganese acts as 
a sort of antidote for sulphur, phosphorus, and perhaps other impurities 
found in steel. It tends to prevent red shortness, promotes the forma- 
tion of fine and uniform crystallization, increases fluidity when the 
steel is melted, and makes it easy to work under the hammer or in rolls. 
Excess of manganese, however, makes steel cold short and causes sur- 
face cracking, especially upon quenching. Certain other elements, 
however, as phosphorus and sulphur, are not only useless but distinctly 
harmful; and the greater the proportion of either present, the more 
inferior the steel. Sulphur tends to make steel " red short " (brittle 
at a red heat) and therefore difficult to forge; while phosphorus tends 
to make it " cold short," and therefore brittle when cold. A very 
minute proportion of either will make a steel worthless for tools of 
almost any sort. Steel for cutting tools is usually expected to contain 
less than 0.02 per cent of either, though in some mushet or air-hardening 
steel the sulphur and phosphorus content have each been found to 
exceed 0.05 per cent. In extra special grades both sulphur and phos- 
phorus are kept below 0.008 per cent. The following table, giving the 
percentages of the various constituents of crucible steel intended for 



24 



HIGH-SPEED STEEL 



tools, indicates approximately the degree of purity required and the 
amount of carbon desirable in steel for the several purposes named. 

TABLE I. 







Man- 


Sili- 


Sul- 


Phos- 




Us:e. 


Iron. 


ganese. 


con. 


phur. 


phorus. 


Carbon. 


Hammers and other battering tools 


99.040 


0.21 


0.21 


0.022 


0.020 0.50 to 0.75 


Knives and shears, hot cutting 


98.935 


0.20 


0.18 


0.020 


0.0150.65 toO. 80 


Drills, reamers, dies, etc . 


98.731 


0.18 


0.21 


0.015 


0.014 0.85 to 1.30 


Lathe tools, knives, chisels, etc. 


98.520 


0.26 


0.20 


0.010 


0.010 1.00 to 1.30 


Razor steel . 


98.265 


0.22 


0.20 


0.006 


0.009 1.30 to 1.50 


Graving tools, etc. 


98.374 


0.16 


0.14 


0.014 


0.0121. 30 to 1.50 



Variations in Composition. — Of course the content of the various 
elements is not definitely established for tools intended for any par- 
ticular use. The practice of different steel makers varies, as also do 
the requirements of users, with respect to the composition of steels 
for special purposes. The above table therefore serves mainly to give 
some idea of the practical applications of the varying proportions of 
carbon and other elements. It will be seen that ordinary carbon tool 
steels, speaking in a general way, are constituted of iron, very small 
proportions of silicon and manganese in combination with carbon rang- 
ing from 0.5 per cent to 1.5 per cent, and minute quantities of impuri- 
ties such as phosphorus and sulphur. The variations possible in the 
carbon content of tools is well illustrated in the analyses of three well- 
known brands of carbon steel in use for lathe tools, whose performances 
were practically identical. The figures are quoted in part from Taylor. 
It is seen that the percentage of carbon varies from 0.681 to 1.240. 

TABLE II. 



Steel. 


Iron. 


Manga- 
nese. 


Silicon. 


Sulphur. 


Phosphorus. 


Carbon. 


Tungsten. 


Ill and Z 
II 

S 


98.524 
98.350 
98.867 


0.189 
0.156 
0.198 


0.206 
0.232 
0.219 


0.017 
0.006 
0.011 


0.017 
0.016 
0.024 


1.047 
1.240 
0.681 


0.079 



Constituents of Self-Hardening Steels. — Besides carbon, manganese 
and silicon, self-hardening steel contains a considerable proportion of tung- 
sten, chromium, molybdenum, vanadium, or certain other like elements, 
generally in definite combinations, as hereafter mentioned. The silicon 
content is practically the same as in carbon steel, while -the manganese 
is usually considerably higher, varying from rather more than one per 
cent to above three per cent according as the tungsten is high or low. 
High carbon also has been the rule in these steels, the percentage running 
say from somewhat more than one, to two per cent, and even higher, 
although the present tendency is toward reducing the carbon content 



NATURE AND CHARACTERISTICS OF THE NEW STEELS 



25 



in high-speed steels, and it is occasionally found very much lower than 
one per cent. Chromium, when present, takes the place of a portion 
of the manganese or the tungsten, which latter ranges from about 4 to 
11 or 12 per cent. The analyses here given are characteristics of these 
steels. 

TABLE III. 



Steel. 


Carbon. 


Tungsten. 


Molybde- 
num. 


Chromium. 


Manga- 
nese. 


Silicon. 


Sul- 
phur. 


Phos- 
phorus. 


Mushet 

Midvale 

B 

C 

D 


2.150 
1.140 
1.615 
1.750 
1.842 


5.441 
7.723 

10.000 
11.589 


4.580 


0.398 
1.830 
3.430 
1.000 
2.694 


1.578 
0.180 
1.650 
1.750 
2.430 


1.044 
0.246 
0.285 
0.060 
0.890 


0.016 
0.007 


0.027 
0.023 


E 


1.220 


7.020 




0.078 


0.300 


0.180 


0.010 


0.017 



A Singular Anomaly. — From the fact of its containing rather more 
than 7 per cent of tungsten, the steel marked E would naturally be 
thought self-hardening, like the others. This however is not the case. 
Though it has a tungsten content about a half greater than that of some 
self-hardening steels, this steel has no such property, when heated to 
the customary temperatures, at any rate. It hardens only on being 
quenched in water, as is the case with ordinary carbon steel. This 
circumstance naturally raises the question as to what causes tungsten 
steel to be self-hard, and likewise that of why steel of any kind becomes 
hard under certain conditions. 

Theory of Steel Hardening. — The' hardening of ordinary carbon steel, 
as is very well known, is accomplished by heating the piece intended 
to be hardened to a red color ranging between a dark and bright cherry 
(something like 735 degrees C. or 1350 F.), and then quenching it in 
a water or other suitable bath to about the normal temperature of the 
air. This process seems to change entirely the structure of the steel 
as seen under the microscope. Careful investigations into the nature 
of these changes have been made, and a number of theories or hypothe- 
ses have been advanced to account for, or rather to explain them. 
The several hypotheses differ more or less among themselves; but those 
that are most generally received agree substantially that steel may 
exist, according to temperature or quenching temperature, in three 
type forms. At temperatures below 735 degrees C. or thereabouts, 
carbon steel is in the unhardened or annealed state. Between 735 
degrees C. (1350 F.) and 820 degrees C. (1510 F.) it exists in a hardened 
state; and above 820 degrees C. it exists in a state harder than the 
first and softer than the second, and is at the same time very tough. 

The Constitution of Annealed Steel. — Steel is not a simple substance 
but, as shown by the microscope, is a conglomerate of crystals of dif- 



26 



HIGH-SPEED STEEL 




Fig. 8. Typical structure of annealed Fig. 9. Structure of hardened high- 

steels. X150. speed steel. X 1,000. 

From Mr. C. A. Edwards' paper on "The Function of Chromium and Tungsten in High-Speed Steel, 
in the Journal of the Iron & Steel Institute. 





Fig. 10. Microscopic structure of high-speed Fig. 11. Microscopic structure of high-speed 
steel ingot as cast. X 150. steel ingot as cast. X 1,000. 

From Dr. Carpenter's "Possible Methods of Improving Modern High-speed Turning Tools." 




3 4 

Percentage of Carbon 



Fig. 12. Constituents of annealed carbon steels. 



NATURE AND CHARACTERISTICS OF THE NEW STEELS 27 

ferent substances. For example, annealed steel containing 0.90 per 
cent carbon, consists entirely of crystals having a pearly appearance 
under the microscope, to which the name of pearlite has been given; 
while in steel of less than 0.90 per cent carbon the microscope shows 
pearlite with varying amounts of a substance called ferrite, the pro- 
portion of which increases as the amount of carbon decreases from 
0.90 per cent. Steel of more than 0.90 per cent carbon consists of 
pearlite again with varying amounts of silvery white crystals of cemen- 
tite. The properties of a steel depend upon the properties of pearlite, 
ferrite and cementite, and upon the proportions in which these substances 
exist in it. 

Graphical Illustration. — The amount of pearlite, ferrite or cementite 
in different compounds of iron and carbon is shown graphically in Fig. 
12, in which the distance from the axis 00' will represent the amount 
of carbon in the material, and the vertical distance above the axis HH' 
in the different areas there shown, will represent the percentages 
of pearlite, ferrite, or cementite present. For example, a line drawn 
from A to A', which is at a distance from axis 00' corresponding to 0.90 
per cent carbon, will be entirely in the pearlite area, and will show that 
this steel contains 100 per cent of pearlite, as before stated. Steel 
represented by the line drawn from B to B' , which is halfway between 
AA' and 00' , will contain 0.45 per cent carbon, and will consist of 50 
per cent pearlite and 50 per cent ferrite. The line drawn from C to C" 
will represent material containing 3.75 per cent carbon, and will lie 
one-half in the pearlite area and one-half in the cementite area, showing, 
therefore, 50 per cent pearlite and 50 per cent cementite. The material 
represented by the line 00' will contain no carbon and consist entirely 
of ferrite, and the material represented by the line PP' will contain 
6.6 per cent of carbon and consist entirely of cementite. By a similar 
method we can determine from the chart (Fig. 12) the proportion of 
pearlite, ferrite, or cementite in steel of any percentage of carbon, it 
being understood that combined carbon only is considered here, free 
carbon, which is what we call graphite, not being a normal constituent 
of ordinary steel. Knowing the properties of pearlite, ferrite and cemen- 
tite, and determining from the chart the proportion of each in steel 
of any given carbon, we can estimate from these data something of the 
characteristics of the steel in question when it is in the annealed condition. 

Properties of Pearlite. — Steel consisting entirely of pearlite has the 
finest crystalline structure of any carbon steel, and this is accompanied 
by the greatest strength and a high degree of hardness. When annealed, 
this steel also has a degree of toughness, so that it can be bent double while 
cold, and a wire of about \ inch diameter can even be tied cold in a knot 
without cracking. Furthermore, it is capable of receiving, by hardening 
or tempering, the greatest possible combination in a carbon steel of 



28 



HIGH-SPEED STEEL 



two valuable properties for cutting work, viz., hardness with absence 
of brittleness. True, tempered steel with less than 0.90 per . cent 
carbon will not be so brittle as pure pearlite steel, but, on the other 
hand, it will not be so hard, either; and tempered steel with more 
than 0.90 per cent carbon will be harder than pure pearlite steel, but 
will also be more brittle. 

Properties of Ferrite. — Ferrite crystals contain theoretically no carbon 
or other impurities; in other words, they consist of pure iron. There 
is no material sold commercially corresponding to pure ferrite, but the 
purest forms of irons, such, as Swedish wrought iron, electrolytic iron, 





Fig. 
Both X 1,000. 



13. 

From 



Ferrite. Fig. 14. Pearlite (lamellar). 

Dr. H. C. H. Carpenter's paper before the Iron and Steel Institute. 





Fig. 15. Pearlite (black) segregated in ferrite. Fig. 16. Gementite (black) with contained 
. . patches of ferrite. 

Dr. H. C. H. Carpenter. Both X 250. 

and the most refined products of the electric smelting furnace, come the 
nearest to it. Those who are familiar with Swedish wrought iron can 
therefore judge of the properties of ferrite, and need not be told that 
they comprise great toughness, softness and ductility, together with 
high electric conductivity and magnetic strength. Crystals of ferrite 
in cutting tools therefore will decrease their ability to cut, but at the 
same time increase their toughness. 

Properties of Cementite. — Cementite crystals contain 6.6 per cent 
carbon and are a chemical compound of iron and carbon, known as 
iron carbide, and having the chemical formula Fe 3 C. Pure cementite 



NATURE AND CHARACTERISTICS OF THE NEW STEELS 29 

does not occur commercially, but its crystals can be separated chemi- 
cally from high-carbon steel, and its properties studied from them. The 
characteristics of cementite are its brittleness, lack of strength, and 
great hardness, which latter is not increased by the ordinary processes of 
hardening or tempering, and cannot be decreased by annealing because 
annealing of pure cementite breaks up the chemical compound and 
converts it into a substance similar to annealed malleable cast iron. 
Even when cementite is mixed with a large proportion of pearlite, 
annealing or even heating to a bright red will break up the compound 
to some extent and precipitate some of the carbon, and this is the 
source of specks of graphite occasionally found in steels containing free 
cementite, that is, in steels with 1.50 per cent carbon and more. 

Effect of Heat Treatment on Steel. — The constituents mentioned above 
are those normally found in steels which have cooled slowly from the 
temperatures at which they were cast or rolled, or in steels which have 
been annealed. All of these constituents are changed by heating to 
higher temperatures, and this is the effect of what is called heat treat- 
ment, viz., hardening and tempering. 

Changes Occurring on Heating Pearlite. — When steel consisting en- 
tirely of pearlite is heated to about 735 degrees C. (1355 degrees F.), 
it undergoes a change in structure and properties. The pearly appear- 
ance under the microscope is lost and we see a homogeneous white 
substance made up of polyhedral crystals to which the name of austenite 
has been given. At the same time the molecule of steel becomes hard 
and loses the power of being attracted by the magnet, so that at this 
high temperature, and above it, steel is non-magnetic so far as the 
ordinary test shows. When the steel is again cooled slowly below this 
temperature, the austenitic structure changes back to pearlite, the 
molecule loses its hardness, and the magnetic property reappears. 

Effect of Heating and Cooling of Pearlite with Ferrite, or of Pearlite 
with Cementite. — Most of the steels used for cutting tools are, by 
composition, chiefly made up of pearlite. Even if there be some fer- 
rite or some cementite present besides the pearlite, the changes occur- 
ring in the steel on heating and cooling have ultimately the same 
effect as that just described, although they occur in a somewhat dif- 
ferent way, which will be explained later. For the present, therefore, 
the changes in all carbon steels will be considered as if they were merely 
from pearlite to austenite and austenite back into pearlite. When 
steel with less than 0.90 per cent carbon is heated to about 735 degrees 
C. (1355 degrees F.), all the pearlite in the steel changes, as before de- 
scribed, into austenite, but the ferrite remains as ferrite for the time 
being. If the heating continues, however, ferrite is gradually absorbed by 
the austenite with each rise in temperature. When there is as much 
as 25 per cent of ferrite (that is, if the steel contains 0.67 per cent car- 



30 HIGH-SPEED STEEL 

bon), the ferrite is not all absorbed until a temperature of about 770 
degrees C. (1415 degrees F.) is reached. When the steel consists of 50 
per cent pearlite and 50 per cent ferrite, the ferrite is not all absorbed 
until a temperature of nearly 800 degrees C. (1462 degrees F.) is reached. 
However, even when there is as much as 99 per cent of excess ferrite, this 
ferrite is all absorbed and the mass converted into austenite by the time 
the temperature has risen to 935 degrees C. (1715 degrees F.). 

If we have cementite present in excess of the pearlite, instead of 
excess ferrite, this cementite is absorbed into the austenite somewhat 
more slowly than the ferrite was. Even with only 15 per cent of excess 
cementite (steel of 1.90 per cent carbon) the temperature will rise 
to the point where melting begins (1150 degrees C. or 2102 degrees F.) 
before the last of this cementite is absorbed. With 9 per cent excess 
cementite (steel of 1.50 per cent carbon) the cementite is all absorbed 
by the time the steel has reached 925 degrees C. (1697 degrees F.). 

It is evident now that all steels are converted completely into the 
non-magnetic austenite, with the hard molecule, upon heating to a 
sufficiently high temperature, and it will not generally be necessary 
hereafter to distinguish in this regard between steel consisting of pure 
pearlite and that consisting of pearlite with cementite or of pearlite with 
ferrite, since the only effect of the excess substance is to raise the tem- 
perature at which the conversion becomes complete. The same relation 
holds good in the cooling of these steels. If there is excess cementite 
or excess ferrite present, as the case may be, the excess is first precipi- 
tated at a somewhat higher temperature than the change from austenite 
to pearlite, depending upon the amount present, and finally, when all 
this excess is precipitated, the residual austenite is converted into 
pearlite. It is to be remembered, however, that if the carbon is below 
0.90 per cent, ferrite is later absorbed into the austenite on heating and 
precipitated in advance on cooling, while, if the carbon is above 0.90 
per cent, cementite is so absorbed and precipitated. 

Lag. — One characteristic of the change from pearlite to austenite on 
heating, and the reverse change from austenite back into pearlite on 
cooling, deserves special notice; that is, it is a somewhat tardy one and 
does not take place instantaneously. On the contrary, it requires a 
few moments for its completion. We express this by stating that the 
change lags behind the temperature to some extent, and this tardiness, 
or lag, is greater the more rapid the heating or cooling is. We may 
liken it to the tail of a comet. If the comet is traveling through space 
at a very rapid pace, its tail will drag out behind it for a long distance, 
but, if the comet is traveling with a relatively low speed, the tail may 
almost keep pace with it, and may even surround it. So, if we heat pure 
pearlite steel very slowly, so that it may take many hours, or even days, 
to reach a bright red heat, the change from pearlite to austenite may 



NATURE AND CHARACTERISTICS OF THE NEW STEELS 



31 



occur all at approximately the same temperature, and if then the steel 
be cooled equally slowly, the change from austenite back into pearlite 
may also be completed all at the same temperature. It has been shown 
that under these conditions of very slow heating and cooling, the change 
from pearlite to austenite on heating will occur at practically the same 
temperature as the reversion from austenite to pearlite occurs on cooling, 
although, with the ordinary rate of heating, the change from pearlite 
to austenite is not completed until a temperature of about 735 degrees C. 
(1355 F.) is reached, and with the ordinary slow cooling in the furnace 



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850 
825 
800 
775 
750 
725 
700 
675 
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FlQ. 17. Curves showing relative location and nature of critical ranges in high-speed and in carbon steels. 
The lower position of the cooling recalescence range, compared with the heating range, is shown also. 

the reversion from austenite to pearlite does not occur until the tem- 
perature has dropped to 690 degrees C. (1274 F.). This difference in tem- 
perature on heating and cooling is not because the change is not a truly 
reversible one, but merely because it is a tardy change and lags behind 
the temperature in both directions. To return to our simile of the 
comet: If we can imagine a comet traveling with great speed from 
west to east,_with its tail extending a long distance behind, it would 
have to pass well beyond a given point before the last of its tail would 
reach that point. If now we should suddenly reverse the direction of 
the comet, the momentum of the tail would still carry it on and the comet 
itself would have had to pass some distance beyond the given point in 



32 



HIGH-SPEED STEEL 



the opposite direction before it would have again dragged the last of 
its tail beyond that point. We might even imagine the return of the 
comet to be so extremely rapid that it would become separated from a 
part of its tail, and leave it behind, beyond the given point we have 
been considering. 

Theory of the Hardening of Steel by Sudden Cooling. — If any carbon 
steel be heated to a high enough temperature, it will be entirely con- 
verted into austenite. If now the steel in this condition be cooled with 
great rapidity, we may bring it to the atmospheric temperature with a 
part of its molecules still left in the austenitic condition; and since the 
austenitic molecule is much harder than the pearlitic molecule, it is on 




No.l 



No.2 



No.3 



]\ T 0.4 



No.5 



Fig. 18. Gradual reduction and final disappearance of marked variations in the curve (apparent dis- 
appearance of recalescence points) on cooling from increasingly higher temperatures. From Dr. 
H. C. H. Carpenter's paper, "Possible Methods of Improving Modern High-Speed Turning Tools." 



this principle that the hardening of steel by sudden cooling is explained. 
No cooling has ever been so rapid, however, as to obtain all the molecules 
in the austenitic condition, because, although the change from austenite 
to pearlite is a tardy one, it is not so slow that we can get away from it 
altogether. 

Influence of Carbon on the Hardening. — There are some conditions, 
however, which aid in keeping some of the steel in the austenitic con- 
dition. One of these is the influence of carbon, which tends to obstruct 
the change and make it more tardy. Thus, with 1.60 per cent carbon 
in steel, and with very rapid cooling, we may find under the microscope 
as much as 70 per cent of the mass in the austenitic condition, but this 



NATURE AND CHARACTERISTICS OF THE NEW STEELS 33 



is about the maximum that has been obtained up to this time by quick 
cooling and carbon content only. 

Again, the importance of carbon in this respect is shown by the obser- 
vation that, unless some carbon is present, we cannot retain any of the 
steel in the austenitic condition, no matter how rapid the cooling or 
what other elements — tungsten, manganese, chromium, etc. — be pres- 
ent. We may cool it with such extreme rapidity that it is brought 
to the temperature of the atmosphere in the austenitic condition, but 
with no more than traces of carbon present it gradually changes over, 
even when cold, to the pearlite condition. We may express this by 
saying that we can catch, or trap, the austenite in the steel by means 
of quick cooling, but we cannot " fix " any of it there except with an 





Fig. 19. Martensite. X 150. 



Fig. 20. Martensite and cementite 
completely separated. X 1,000. 



influential proportion of carbon. The tendency of austenite to revert 
to the normal, or pearlitic, condition at all temperatures below 700 
degrees C. (1292 F.) is so strong that it will do so even when cold unless 
carbon is present as a fixing agent. The colder the steel, the more 
slowly the reversion proceeds, however. 

Martensite. — In order to understand the nature of high-speed steels 
and the reasons why tungsten and other elements, together with the 
special heat treatment required, produce the effect they do, we must 
recognize another constituent of steel which is intermediate between 
pearlite and austenite, and to which the name of martensite has been 
given. Martensite is probably never a normal constituent of steel, but 
occurs only as a transition stage in the change from austenite 1 to pearlite. 

1 Alpha, Beta, and Gamma Forms of Iron. — Although a knowledge of the nature of 
austenite, martensite, troostite, and pearlite is not necessary to an understanding of 
high-speed steels, there are many no doubt who wish to know as much about the tools 
as it is possible to learn. In order for us to understand the distinction between these 
different constituents in hardened and tempered steels, we must first understand the 
varying and compound nature of iron itself. 

Pure iron at atmospheric temperatures is the most magnetic substance known to 
man, with the exception of a recently discovered silicon steel alloy, which it is not 
necessary for us to discuss here. When this pure iron is heated to and above a tem- 



34 



HIGH-SPEED STEEL 




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NATURE AND CHARACTERISTICS OF THE NEW STEELS 35 

That is to say, austenite changes first into martensite, but, as this has 
no normal place in steel at any temperature, it should change at once 
into pearlite. It is to be observed, however, that the change from 
austenite to martensite is a very quick one and most difficult to prevent 
or obstruct, while the change from martensite to pearlite is a much 
slower one. Martensite is harder and more brittle than austenite, and 
also more, bulky; so that the steel expands when it changes from austen- 
ite to martensite, and then contracts again when its proceeds further 
to the pearlite stage. This expansion explains the occasional bursting 
of steel tools during hardening. 

Fixing the Austenite and the Martensite.- — The usual heat treatment 
for hardening tools, which consists in raising them to a bright red heat 
and then plunging into cold water, is not 
quick enough to prevent the change from 
austenite to martensite. Austenite can only 
be fixed at atmospheric temperatures when 
(1) the cooling begins from a strong white 
heat, when (2) it is the most rapid possible, 
and when (3) the carbon is over 1 per cent. 
The method of cooling usually employed for 
this extreme rapidity is to plunge the white 
hot steel into iced brine or some other liquid 
cooled well below the freezing point of water. FiG< 23- Austenite . x 90a 
Even under these extreme conditions only a 
part of the austenite can be preserved unaltered. 

The usual process of hardening produces martensite in the steel, 
whose hardness, as has been stated, is greater than that of austenite. 
Unfortunately, however, this hardness is. accompanied by too much brit- 
tleness to withstand the shocks of service, and generally some of it has to 
be sacrificed for the sake of durability. This sacrifice is made by means 
of a tempering process. 

Tempering. — It has been already said that the colder the steel, the 
slower the change from austenite to pearlite, after it has been trapped 
by a hardening process. Advantage is taken of this fact in the com- 

perature of 760 degrees C. (1400 F.), it loses almost completely the power of being 
attracted by a magnet. At the same time the iron changes its electrical conductivity, 
its form of crystallization, and other properties. If the heating be continued, the 
form of crystallization and other properties change again at a temperature of 890 
degrees C. (1634 F.). In short, pure iron can radically change some of its properties 
at different temperatures without changing its composition or individuality. Because 
the iron remains iron all the time, we therefore call these different forms in which it 
occurs "allotropic modifications." That condition in which it exists at atmospheric 
temperatures we call Alpha iron (a); that at temperatures between 760 and 890 degrees 
C. (1400 and 1634 F.) we call Beta iron (/?); and that above 890 degrees C. we call 
Gamma iron (7), 




36 



HIGH-SPEED STEEL 




FrG. 24. Curves showing clearly the lower critical point — that connected with the phenomena of 

tempering. 
Movements of the differential galvanometer, about fa size. Dr. H. C. H. Carpenter, Journal of the Iron 

and Steel Institute. 




Carbon 


Self -hardening 


High Speed 


Tool 


Tool 


Tool 


No.l 


No.2 


No.3 



Fig. 25. Curves comparing softening or tempering ranges of carbon, self-hardening, and high-speed 
steels. From Dr. Carpenter's paper, "Possible Methods of Improving Modern High-Speed Turning 
Tools." 



NATURE AND CHARACTERISTICS OF THE NEW STEELS 



37 



mon process of tempering. If we have fixed some martensite in a carbon- 
steel tool, we can " let it down " toward the pearlite stage to any desired 
degree by gently heating the tool. Softening begins by this process at 
a temperature of about 200 degrees C. (392 F.). This proceeds more and 
more as the temperature is raised, and usually is as complete as desired 
before we reach a temperature of 400 degrees C. (752 F.). All temper- 
ing after hardening will therefore take place at the temperatures between 
those mentioned, and in fact 99 per cent of all tempering of carbon-steel 
cutting tools is between 200 and 300 degrees C. (392 and 572 F.), while 
it is only those comparatively few tempered articles whose hardness 
must be plentifully sacrificed for the sake of toughness, such as springs, 
screw drivers, cold chisels, etc., in which we let down-the martensite by 
tempering above 275 degrees C. (527 F.). 

Temper Colors. — Nature has fortunately provided a tolerably accurate 
and convenient pyrometer whereby the extent of tempering may be esti- 
mated by eye; for, at about 200 degrees C. (392 F.) the steel assumes a 



Fig 





Fig. 27. 



Fig. 28. Heated to 680 degrees C. X 1,000. Fig. 29. Heated to 730 degrees C. X 1,000. 
Change in microscopic appearance of high-speed steel due to "low heat" treatment. Composition of 
steel shown in Figures 36 and 37, C 0.68, Cr 3.01, W (tungsten) 19.37; that shown in Figures 34 and 
35, C 0.67, Cr 6.18, W 12.5 per cent. 

very light lemon color. As the temperature rises, the color deepens to a 
faint yellow and then to a straw, pink, light purple, and so on, to a deep 



38 HIGH-SPEED STEEL 

blue. The approximate correspondence of these colors with the differ- 
ent temperatures is shown in the frontispiece of this book. The 
temper colors are due to a film of iron oxide which forms on the bright 
surface of the steel and which gets thicker and thicker as the heat 
progresses. 

Tempering in Oil. — Steel is sometimes tempered, not by the com- 
bination process just mentioned, whereby it is first brought to the marten- 
siti'c stage by hardening and then let down towards the pearlite stage 
by warming until the desired " temper " is obtained, but by cooling 
with intermediate rapidity in the first instance, such as by plunging into 
oil when at a bright red heat, instead of into water. In this way the 
martensitic stage is not so completely fixed, and the moderately rapid 
cooling produces the same effect as if we first cooled with greater speed 
and then let down the martensite by tempering. 

Troostite. — Tempered steel consists wholly or partly of troostite, 
which is a transition stage between martensite and pearlite. Troostite 
is softer and tougher than martensite, so that the toughness of tempered 
steel will depend upon the relative proportion of troostite in it, and this 
latter will depend in turn upon the amount of tempering. Some troos- 
tite is found even in hardened steel unless it has been quenched from 
a temperature nearly a white heat and far above the " critical point," 
i.e. the point at which pearlite changes to austenite on heating, and 
austenite reverts to pearlite on slow cooling. 

Nature of Austenite, Martensite, Troostite, and Pearlite. — In the present 
incomplete state of our knowledge of the constituents of hardened and 
tempered steels, we must accept all theories ? somewhat tentatively. 
However, the indications at present are that austenite is a solid solution 
of carbon 2 in gamma iron, that martensite is a solid solution of carbon 
in beta iron, and that troostite is a solid solution of carbon in alpha 
iron. Theoretically neither beta nor alpha iron can be maintained in 
solid solution with carbon, and therefore austenite is the only stable one 
of these solutions, and martensite and troostite must be considered as 
unstable constituents and merely transition stages between austenite 
and pearlite. In other words, when the solution of gamma iron falls to 
the temperature at which it breaks up, it changes to the solution of beta 
iron; this being an abnormal solution at once breaks down into the 
solution of alpha iron (provided of course that it is not obstructed), 
and the alpha solution being also abnormal breaks down into pearlite, 
which is not a solution at all but a mere mixture of crystals of ferrite 

1 The theory of steel hardening here outlined is substantially that proposed by Pro- 
fessor Howe, which is perhaps as widely accepted as any other. 

2 Where we speak of solutions of carbon in gamma, beta, or alpha iron, it is to be 
observed that the carbon may be dissolved directly in the iron, Or it may be in the 
form of iron carbide, or cementite, and this dissolved in the iron. 



NATURE AND CHARACTERISTICS OF THE NEW STEELS 39 

-and cementite so fine in structure that the high powers of the micro- 
scope are necessary to show its structure. 

Effect of Manganeseon Hardening. — Manganese has the effect of 
delaying the change from austenite to pearlite, and of acting as a fixing 
agent for the austenite, but both of these influences are different in kind 
from the influence of carbon. Carbon hinders the change by making 
it slower. Manganese, on the other hand, makes the change occur at 
a lower temperature. That is to say, instead of the change on heating 
and cooling taking place at about 700 degrees C. (1292 F.) it occurs 100 
or so degrees lower when there is 1 per cent of manganese present. 
With 2 per cent of manganese, the change occurs at a lower tempera- 
ture still, and finally when there is as much as 12 to 20 per cent of 
manganese present, it occurs at a temperature below that of our atmos- 
phere. In other words, as 12 per cent manganese steel cools from the 
temperature at which it is made, it ordinarily never gets so cold that 
it will change over from the austenitic to the pearlitic condition. There- 
fore, manganese steel, which, as usually made, contains between 12 and 
15 per cent of manganese, is what is called a self-hardening steel, mean- 
ing that it is normally in the austenitic or martensitic condition, and 
that even annealing will not change it to the pearlitic condition. 

Heat Treatment of Manganese Steel. — As has been shown, the change 
from austenite to martensite is a very quick one, and difficult to prevent. 
Thus even manganese steel, if allowed to cool slowly in the mold into 
which it is poured, will be wholly or partly in the martensitic stage at 
atmospheric temperatures. In this condition it is not only very hard, 
but also very brittle. By heating it to a white heat (over 1000 degrees 
C. or 1832 F.), and cooling very rapidly, as by plunging it into ice-water, 
we can, however, entirely fix the austenitic stage in this steel. This 
fixation of the austenitic stage makes the steel not so hard as it was 
when in the martensitic condition, but still very much harder than 
in the pearlitic. It is also very tough; but unfortunately it has such a 
low elastic limit that the thin edge of a tool will not stand up under 
the shocks of service, but crumbles away, so that manganese steel is 
not suitable for making cutting tools. 

Effect of Nickel on Hardening. — The effect of nickel on hardening is 
the same in kind as that of manganese, but it takes about twice as much 
nickel to produce this effect. As ordinary nickel steel contains usually 
only 3J per cent of nickel, and as it requires about 25 per cent to bring 
the temperature of the change below that of the atmosphere, commercial 
nickel steel is not a self-hardening steel, but is used for other purposes. 

Effect of Chromium on Hardening. — The effect of chromium on harden- 
ing appears to be similar to that of carbon in so far as making the change 
more slow is concerned. With 1 to 2 per cent of chromium in steel and 
about 1 per cent of carbon, we can get a much more intense degree of 



40 



HIGH-SPEED STEEL 



hardness by means of rapid cooling, but not without. That is, the steel 
is not self-hardening. Although chromium alone will not make a steel 
self-hardening, yet chromium with a few per cent of manganese (much 
less than that present in manganese steel) will produce this result. 
Chromium also has the effect of increasing the elastic limit of steel, 
especially when it is combined with vanadium. The hardness imparted 
by chromium is not accompanied by as much brittleness as that induced 
by carbon. When the steel contains chromium, the amount of carbon 
is reduced, since the extreme of hardness is not desired, and toughness 
may be gained thereby. Tools below 1.50 per cent of chromium are very 









0.39 




0.41 










0.77 




Percentage of Carbon 
0.86 0.71 










1.27 














































fl ■ 








































































ol 












jJjHe'el 




























































p* 
















































































, 










































































k 






<9 












& 


,l'K 


d-* 


























































> 














't 
























































> 




























, 


'/ 




















































\ s 




























— I 


— 1 — >— 


































































LTmiT 




"~ 


- 


J 1 
















































\ 


\ 












V 5 














«, 










































# 












le<J " 














s 








\ 




















1 


>£fr e ; 




"" 
















































- 
























1 






























































E 


a.s 


ic 


Limit 




j! 


Am 


eaied 


Stee 
































^..- 












































































- 


































































V 












„ 










































































"., 


, 























1 2 3 4 5 6 7 a 9 10 11 12 13 14 

Percentage of Chromium 

Fig. 30. Effect of chromium on tensile strength and elastic limit. From "Steel and Its Uses," by 

Edmund F. Lake. 

tough and effective in cutting soft materials. High-chromium tools, 
containing up to 5 or 6 per cent chromium, are very hard and effective 
upon refractory materials. 

Mushet Steel. — Chromium with tungsten will also produce a self- 
hardening steel, although neither of these elements alone will have any 
such effect. The combination of tungsten with a small amount of 
manganese will also reduce the temperature of change below that of the 
atmosphere. The famous old mushet steels, which were the first self- 
hardening steels, were of this composition and character. Without 
either a little chromium or a little manganese, however, no amount of 
tungsten would produce such an effect. The anomaly exhibited by 
the last steel mentioned in Table III is now explained. That steel con- 
tains more than 7 per cent of tungsten, but only 0.3 per cent of manga- 
nese and little more than a trace of chromium, neither of which is 
sufficient in amount to make the steel self-hardening. 

Effect of Tungsten. — Tungsten acts first as a strong obstruction to 
all the steps in the change from austenite to pearlite, so that when we 
have 7 per cent or more of tungsten present, a moderately rapid cooling, 
even such as allowing the bar to cool in the air, will prevent the change 
to pearlite. Indeed, when tungsten steels are to be annealed and the 



NATURE AND CHARACTERISTICS OF THE NEW STEELS 



41 



pearlite stage produced, it is necessary that the cooling shall be very 
slow indeed, occupying several times as long as the annealing of normal 
carbon steels. 

Tungsten acts secondly as a powerful fixing agent for martensite. 
It has been already shown that martensite is not stable in normal carbon 
steel even after it has been induced there by hardening, unless the metal 
be kept co'ol. Warming it up to the so-called temper heats changes the 
martensite over to troostite, and if the heating be continued, even the 
effective hardness of troostite is lost long before the steel reaches a 
red heat. The presence of 7 per cent or more of tungsten, however, 
increases the stability of martensite so much that the steel may be heated 
well above the tempering heats before the martensite even begins to 
break down into troostite or pearlite. 

Red Hardness. — Red hardness is the quality of hardness when at a red 
heat, and tungsten imparts this to steel under certain conditions* for a 



c. 




Heating Curves of High-Speed Steels 




1000° 


1 


"be 

C 


900° 




15 '** 

OS £ 

a 
r 1 a) 


/ r 


Centigrade 

8 

o 


<T "^CL". -"835° C. 




m 


,4P .:#" 






1? 700° 
C 


The Kange in which 
Red-Hardness is lost 




B 6 25° 


C. i 


f ^ The Temperature of the f 






as 

g 1 600° 




^'"•Low" Heat Treatment r 




500° 






400° 





. 0.85 per cent.. 



Chromium - 
Tungsten 



.12.5 



. Chromium - 
.Tungsten 



_ 0.55 per cent. 
_3.5 « « 
.18.5 tt •! 



(The Steels were previously heated to 1200° C.) 

Fig. 31. Curves showing the location of critical points Ar u Ar%, and Ar 3 , in high-speed steels, and the 
location of the range wherein red-hardness is lost. Taken from Dr. Carpenter's papers. 



time at least. That is to say, we may cut with a tungsten steel at so 
rapid a rate that the point of a tool will reach that temperature where 
it almost begins to glow in a dark room, and still the steel will retain its 
hardness for many hours. Finally, however, the hardness is lost to the 



42 



HIGH-SPEED STEEL 



steel by remaining continually at this temperature, and modern practice 
is opposed to working the tool at such a rapid rate. (See Appendix B.) 

Heat Treatment of High-Speed Steels. — It is now possible to explain 
the theory of the effect produced by the special heat treatment applied 




Fig. 32. (X150). Fig. 33. (X 1,000). 

Microscopic structure of the nose of a high-speed steel tool after cutting at its maximum speed for 20 
minutes. Long white austenitic streaks imbedded in a martensitic structure. From C. A. Edwards' 
paper, "The Function of Chromium and Tungsten in High-Speed Steel," Journal of the Iron and 
Steel Institute. 

to high-speed tools. The first treatment, that is, a moderately rapid 
cooling from a very high temperature, is sufficient to retain the steel 




Fig. 34. Tool used in Taylor experiments run at a high cutting speed upon a steel forging. The nicks 
were filed in with an ordinary file after the tool was taken off the work. The tool evidently is quite 
soft, in spite of having at the same time a high degree of red-hardness to enable it to stand up under 
heavy duty. From Taylor's Report. 



chiefly in the austenitic condition by virtue of the tungsten present. 
The second, or low-heat, treatment then changes the . austenite partly 
or wholly into martensite, thus further increasing the cutting efficiency 
of the tool by increasing the hardness. Subsequently, the tungsten 



NATURE AND CHARACTERISTICS OF THE NEW STEELS 43 

present acts by preserving the martensite even when the steel is heated 
up nearly to a red heat by the friction of work. 

If we ask why it is necessary first to cool the steel from so high a tem- 
perature as to obtain the austenitic structure, and then to let down 
this austenitic structure to martensite by reheating instead of cooling 
for martensite in the first instance, it is to be observed that, unless the 
cooling begins at a very high heat, austenite is changed in part to troos- 
tite, and then the tungsten present is not sufficient to prevent the 
softening proceeding still further, when the steel is heated up by the 
friction of rapid work. In short, if we allow the change to progress 
beyond a certain point, it is difficult to check it thereafter. 

Influence of Vanadium on Steel. — The influence of vanadium is not 
thoroughly investigated as yet. It has a strong affinity for oxygen and 
therefore doubtless acts to purify the metal of this injurious impurity. 
Further than this, its influence when alone in carbon steel does not 
seem to be always of great benefit, although it has never been shown 
to have an evil effect. In combination with other elements, such as chro- 
mium and nickel, vanadium greatly improves the quality of steel, especially 
after special forms of heat treatment, as shown by the following test 
of a steel containing 0.34 per cent of carbon, 1 per cent of chromium, 
and 0.17 per cent of vanadium: 

Elastic limit, lbs. per sq. in 222,200 

Tensile strength, lbs. per sq. in 227,300 

Elongation, per cent 11.5 

Reduction of cross section, per cent 42.0 

The amount of vanadium present should never much exceed 0.20 per 
cent, although more than this must be added, for some of the vanadium 
is lost, probably, by passing into the slag together with the oxygen which 
it removes. This purification alone is hardly sufficient to explain the 
markedly beneficial effect of vanadium on high-speed steels, but this 
subject will have to be left for future investigation. 

Influence of Titanium. — The only other element whose addition to 
steel is commercially important to-day is titanium. This has a strong 
affinity for nitrogen; and it may exert a good effect by removing this 
impurity, although this is as yet only surmise. The improved wearing 
qualities of steel rails containing titanium has been proved, and it is known 
also that it increases the strength of cast iron. It is not yet reported 
that this element has been tried to any important extent in tool steels. 

Uranium. — The ores of uranium, on the other hand, occur but rarely. 
Some experiments have been carried on to determine the utility of 
uranium as a high-speed steel alloy; but thus far it has not been shown- 
to add any important qualities which are not obtainable by the use of 
cheaper elements already much used. 



44 HIGH-SPEED STEEL 

Aluminum. — Aluminum, often used in the manufacture of ordinary 
steels as a purifier during the making process, does not appear to add 
any desirable quality to high-speed steel, and as far as can be learned is 
not much, if at all, used in its manufacture. 

Tantalum. — Until recently very little was known of what is perhaps 
the most curious of all the metals, tantalum. For the matter of that, a 
good deal still remains to be learned concerning it. Like most other 
hardening elements, it readily combines with carbon; but the carbides 
thus formed are not soft, as is the case with the others, but very hard. 
A small amount of carbon is sufficient to carbonize a large amount of 
tantalum. It is considerably more than twice as heavy as iron, bulk for 
bulk; is about as hard, when in the annealed state, as soft steel; and 
has a tensile strength nearly a third higher. When hardened by alter- 
nate heating and hammering, metallic tantalum becomes so hard that a 
diamond drill will scarcely touch it, at the same time retaining a remark- 
able degree of toughness. No information is at hand as to its specific 
influence upon high-speed steel; but it is known that one maker uses 
tantalum in steel for drills, dies, and tools of like nature. The strong 
affinity of tantalum (when hot) for oxygen makes it necessary to heat 
tantalum steel under special conditions such as will prevent contact of 
the heated steel with the air. The electric furnace is mostly used for this 
purpose. Tantalum ores are of rare occurrence, and ferrotantalum, the 
form in which it is used, is costly. 

Importance of Manganese. — The importance of manganese in the 
manufacture of steels of all kinds, and its influence upon high-speed 
steel in combination with tungsten, have been already mentioned. Like 
nickel and chromium, manganese seems to hinder the formation of the 
double carbides of tungsten and molybdenum. Steel containing these 
elements in combination with a sufficient proportion of manganese 
(or of nickel or chromium) therefore are self-hardening without the 
high heat treatment, though they are not necessarily high-speed 
to any considerable extent, even when they receive that treatment. 
Very high manganese makes steel cold-short and susceptible to fire- 
cracking. Low manganese does not, apparently, affect the property of 
red-hardness or temper resistance; but it does tend toward strength 
and toughness in the body of a tool, while at the same time allowing it 
to be readily forged and annealed. The apparent effective range of 
manganese content lies between about 0.2 and 1.2 per cent. If above 
2.0 per cent in connection with low carbon, the steel is likely to be very 
hard and brittle, unless the percentage is also above 6.0 per cent. The 
tendency seems to be to substitute chromium for manganese above 1.2 
per cent. The chromium seems to do the work better than manganese 
beyond this point, and does not cause the undesirable tendencies above 
mentioned. 



NATURE AND CHARACTERISTICS OF THE NEW STEELS 45 

Silicon. — Silicon, like manganese, has an important function in the 
manufacture of steel; but in the proportion usually met with, has no 
important influence upon the structure or physical properties. An 
iron-silicon alloy containing from 5.0 to 15.0 per cent of the latter can be 
readily forged cold, like nickel; but is not forgeable at a red heat. Very 
high silicon increases the hardness of steel, and at the same time greatly 
increases the brittleness. A singular circumstance is that an alloy of 
about 20.0 per cent silicon becomes much harder when slowly cooled than 
when quenched. In high-speed steel high silicon sensibly lowers the 
cutting speed, though up to about 3.0 per cent it is said to increase the 
efficiency, especially upon hard material. Taylor indicates that 0.15 
per cent or thereabouts is, all things considered, most satisfactory. 

Sulphur and Phosphorus. — Sulphur and phosphorus are as difficult to 
keep out of high-speed steel as out of other steels; and while they' prob- 
ably are slightly less harmful than in carbon steel, nevertheless should 
be kept as low as possible. The former tends to make steel red-short, 
and the latter cold-short. More than 0.03 per cent of phosphorus is 
ruinous. 

Theoretical Formulas for High-Speed Steel. — It is seen from the above 
that while there are several agents more or less adapted to steel harden- 
ing, most of them are not well enough known, possess certain negative 





Fig. 35. X 150. Fig. 36. X 1,000. 

Microscopic structure of mushet (self-hardening) steel. From Dr. Carpenter's "Possible Methods of 

Improving Modern High-Speed Steels." 

qualities, or are too rare to be available at the present time. Tungsten, 
molybdenum, chromium, manganese, and vanadium, besides possibly 
titanium, are now in general use to give tool steel properties not conferred 
by carbon or to enhance the influence of that element. As has been 
already mentioned, the influence of any of these elements separately is 
not necessarily the same as when combined with others; and indeed in 
most cases there seems to be considerable difference, as for example in 
the case of tungsten and manganese or tungsten and chromium, already 



46 



HIGH-SPEED STEEL 



referred to. So far, therefore, it has not been possible to work out 
theoretically a formula for a high-speed steel mix. The method has 
necessarily been that of cut-and-try, further development being along 
the lines indicated by more or less successful mixes. 

Relation of Mushet and High-Speed Steel. — If mushet steel was not 
strictly speaking high-speed, it was at any rate the forerunner of high- 
speed steel; and the development of the latter grew out of the former. 
Analyses of self-hardening steels have been previously given. The 
composition of the original self-hardening steel, R. Mushet's Special, has 
been frequently stated to be approximately as follows: 

Carbon 2.0 per cent 

Tungsten 5.0 per cent 

Chromium 0.5 per cent 

Manganese 2.5 per cent 

Silicon 1.3 per cent 

Analyses of several typical self-hardening steels are shown in a pre- 
ceding table; while analyses for a considerable number of high-speed 
steels are given in Appendix A. The average composition of some 
twenty brands of self-hardening steel is shown in the table below, together 
with the average composition of about twenty-five brands of good high- 
speed steels. 

TABLE IV. COMPOSITION OF SELF-HARDENING AND HIGH-SPEED STEELS. 



Carbon 

Tungsten ' . . . 
Molybdenum 
Chromium. . 
Vanadium 3 . . 
Manganese . . 

Silicon 

Phosphorus 4 
Sulphur 4 . .. . 



Self-Hardening. 



Aver- 
age. 



1.8 
7.3 
4.58 
1.6 

1.8 
0.56 
0.032 
0.015 



High. 



2.4 
11.6 

3.4 

3.5 
1.04 
0.080 
0.050 



Low. 



1.1 
4.5 

0.07 

0.08 
0.16 
0.016 
0.004 



High-Speed. 



Aver- 
age. 



0.75 
18.00 
3.50 
4.00 
0.30 
0.13 
0.22 
0.018 
0.010 



High. 



1.28 
25.45 
7.6 
7.2 
0.32 
0.30 
1.34 
0.029 
0.016 



Low. 



0.32 
14.23 
0.00 
2.23 
0.00 
0.03 
0.43 
0.013 
0.008 



Recommended 

by Taylor as Best 

All-round Cutting 

Steel. 



0.682 
17.81 

5.95 
0.32 
0.07 

0.049 



0.674 
18.19 

5.47 
0.29 
0.11 
0.043 



1 Tungsten is used in all but one of the steels analyzed. In combination with molybdenum the 
percentage of tungsten is lower than that given. 

2 Molybdenum was found in but one of the self-hardening, and in six of the high-speed steels, 
in the latter always (with one exception) combined with tungsten. The minimum percentage so 
combined was found to be 0.48. 

3 Found in but three of the steels analyzed. 

4 The exceeding difficulty of determining such infinitesimal quantities as are involved in the 
separation of phosphorus and sulphur makes these figures more or less uncertain. In most cases it 
is possible only to say that traces of these elements exist. 



Mushet and High-Speed Steels — Differences. — A first glance at the table 
does not reveal any striking or apparently essential difference between 



NATURE AND CHARACTERISTICS OF THE NEW STEELS 47 

high-speed and self-hardening steel; and indeed it is stoutly maintained 
that there is no such essential difference — that mushet steels are high- 
speed if treated by the high-heat process. When it is remembered 
that it was with self-hardening or mushet steels that Taylor and White 
were experimenting, and that it was these that yielded high-speed steels 





Fig. 37. X 150. Fig. 38. X 1,000. 

Microscopic structure of high-speed steels. Typical of all containing more than 9.0 per cent tungsten 
and 3.0 per cent chromium. From Mr. Edwards' paper. 

when subjected to the high-heat treatment, it becomes evident that 
though not now identical, there is a very close relationship between 
them. An inspection of the table above will show that the chief 
differences in composition are these : 

High-Speed Self-Hardening 

Carbon Medium or low, 0.3 to 1.3% High, 1.0 to 2.5% 

Tungsten High, 14.0 to 25.0% Low, 4.5 to 12.0% 

Chromium High, 2.0 to 7.0% Low, 0.1 to 3.5% 

Manganese Low, 0.03 to 0.3% High, 0.08 to 3.5% 

The differences, it will be observed, are entirely of degree, and not of 
kind. The total amount of alloy is very largely increased, and in every 
case the proportions of the ingredients named are inverted. This of 
course makes a very great difference in the qualities, though not neces- 
sarily in the characteristics of high-speed and of the older self-hardening 
steels. The quality which particularly characterizes high-speed steel is 
red-hardness, the property of resisting the drawing of the temper when 
heated even to a red color. But red-hardness is imparted to the alloy steels 
(suitable ingredients being present) chiefly by the high-heat treatment — 
that is, by heating these steels to the point where they become austenitic, 
or gamma. It would be natural to suppose that all austenitic steels 
necessarily are red-hard to a high degree. This however does not seem 
to be the case, although the two conditions usually are found together in 
some degree. 

Steel for Universal Use. — Thus far, in high-speed steel practice, the 
disposition on the part of users, as well as of makers, has been to use 



48 



HIGH-SPEED STEEL 



one steel for all purposes, tools for cutting hard as well as soft materials 
(wood among the rest), forming dies, crushers or hammers, rock drills, 
and all the rest of the category of tools. Most manufacturers make 
rather extravagant claims for universal high efficiency on behalf of their 
particular steels. It is true that some steels on the market come pretty 
close to fulfilling the various conditions requisite to universal service, 
not only making good cutting tools for hard and soft metal and wood, 
but being suitable also for forming dies, crushing tools, hammer tools, 
and the like. For the most part however high-speed steels are adapted 
to particular rather than general service. Thus a steel highly efficient 
in cutting hard material often is not so on soft; and one well suited to 
cutting is not very likely to be well adapted to forming dies and the like. 
Mr. Taylor mentions one steel tried in his experiments as being superior 
to all others in all kinds of metal cutting, and gives its composition as 
shown in Table V, and also in Table IV above. For the sake of com- 
parison the Jessop, Mushet Special, and the original Taylor- White steels 
also are included in the table. The figures indicate percentages, except 
as noted. 

TABLE V. 



Steel. 



Jessop carbon 

Mushet Special 

Original Taylor- White 

Best modern high-speed steel 



Car- 
bon. 



1.047 
2.150 
1.850 
,0.674 
0.682 



Sili- 
con. 



0.206 
1.044 
0.150 
0.043 
0.049 



Manga- 
nese. 



0.19 
1.58 
0.30 
0.11 
0.07 



Tung- 
sten. 



5.44 

8.00 

18.19 

17.81 



Chro- 
mium. 



0.207 

0.040 

3.80 

5.47 

5.95 



Vana- 
dium. 



0.291 
0.32f 



Speed. 



16 
26 
60 

100 



1 Cutting speed in feet per minute at which a tool is completely ruined at the end of twenty 
minutes, working on medium steel. 



Though nothing is said as to its efficiency in tools other than those 
for metal cutting, the composition of this steel indicates that it is also 
good for all tools requiring toughness and wearing quality; so that 
it may fairly be classed as an all-round steel. Other things equal it would 
be highly desirable to have in a shop, or set of shops, one all-round steel 
equally and in a high degree efficient in all sorts of work commonly 
turned out. The need for so many varieties of tool steel heretofore has 
been a source of great inconvenience, frequent mistakes, and untold 
annoyance — all which would be dissipated could a single steel be 
economically substituted for all the varieties now in use. 



CHAPTER IV. 

STILL NEWER STEELS. 

Need for Intermediate Steels. — After the metal cutting industries had 
begun to adjust themselves to the new situation following the introduction 
of high-speed steels, the use of self-hardening or mushet steels rapidly 
decreased until very little call for it existed and most manufacturers 
ceased making it altogether, putting out instead a more or less excellent 
quality of the high-speed kind. This however was not for some little time 
after the Taylor- White discoveries became public. The self-hardening 
steels had come into rather general use in difficult jobs, and in pro- 
gressively managed shops were used to a considerable extent on all 
sorts of work; and so, while the new steels with their wonderful 
possibilities were justifying themselves and establishing their place, 
very properly there was a disposition to hold fast to that which 
had already proved itself, rather than take up something but little 
known or tried. Recently there has again come to be some demand for 
steels which, while possessing the qualities of high-speed steel to a 
moderate degree, enough to adapt them to kinds of work not requiring its 
high cutting powers and red-hardness, could be bought at a price consid- 
erably below that of high grade air-hardening steel; and a number of 
manufacturers have brought forward steels to fill this gap. 

Field for Semi-High-Speed Steels. — Certain of these are claimed to be 
especially adapted to use in blanking, drop, and forming dies, and tools of 
like nature which are subjected to severe wear but which generate no 
considerable amount of heat while at work. High-speed steel has lately 
come into use for such purposes, but where the dies are subjected to 
tremendous pressures as, say, in the case of cold heading work, they are 
liable to split. It remains to be seen how well these special or "inter- 
mediate " steels will fit into such uses as a substitute for the high-speed 
kind. 

There doubtless are many classes of work wherein a steel of less endur- 
ance than the best high-speed varieties would answer every requirement 
and yield results equally as good; jobs where extremely high speeds 
or heavy cuts are in the nature of the case impracticable, or as in 
certain wood-working operations, where a cutter of higher endurance 
than one of the best carbon steel would have an almost indefinite life 
anyway. In such cases, it would seem, the high cost of air-hardening 
steel imposes an unnecessary expense in tool equipment. 

49 



50 HIGH-SPEED STEEL 

Nature of the Intermediate Steels.— Most of the so-called "intermedi- 
ate " steels are nothing more nor less than mushet or self-hardening 
compositions, although some of them seem to be manganese rather 
than tungsten steels. A typical example of such a "special," "inter- 
mediate," or " semi-high-speed " steel, of excellent sustaining power 
and not exceptionally hard to treat, has the composition: 

Per cent. 

Carbon 1 . 190 

Tungsten 7 . 560 

Chromium 3 . 340 

Manganese . 460 

Phosphorus . 024 

Sulphur 0.025 

Silicon . 200 

Another gave this analysis: 

Per cent. 

Carbon . 94 

Tungsten 4.78 

Chromium . 69 

Manganese 0.27 

Phosphorus 0.01 

Sulphur 0.01 

Silicon 0.11 

Both these steels, it will be observed, are rather lower in carbon than 
most mushet steels were, and the first is rather higher in tungsten while 
the second is lower in chromium. A third, which scarcely falls within 
the mushet class is thus composed: 

Per cent. 

Carbon 1 . 25 

Tungsten 2 . 25 

Chromium . 28 

Manganese . 85 

Silicon 0.21 

The last is advertised and sold specifically as a " finishing " steel; 
and it unquestionably gives excellent results in this particular kind of 
work. Besides these there are a number of other steels on the market, 
sold for tool use, whose tungsten content (or molybdenum equivalent) 
ranges from near that essential in a high grade high-speed steel down to 
that indicated in the analyses above. Most of these are sold as high- 
speed steels, though at a lower price than is customary for those of the 
highest grade, and to a greater or less extent they are so, if the chromium 
content corresponds with the tungsten. 

Still another steel very widely advertised as an " intermediate " 
steel, and doing exceedingly well in certain classes of work, including 



STILL NEWER STEELS 51 

blanking and stamping, as well as cutting wood and metals of moderate 
hardness, has this anomalous composition: 

Per cent. 

Carbon 1 .03 

Tungsten . 46 

Chromium 

Manganese . 30 

Phosphorus . 025 

Sulphur . 009 

Silicon 0.008 

This is represented as an especially dense steel requiring very slow 
and careful heating to a cherry red (800 to 850 degrees C. or about 
1,470 to 1,550 F.) for cutting tools, and somewhat lower for tools intended 
to withstand pressure or blows. It is water-hardening, as might be 
supposed from its composition, and requires the temper to be drawn as 
in the case of carbon steel tools. It is claimed to be at least 50 per cent 
tougher than carbon tool steel — though that is about what it seems 
really to be. Several other steels sold for about the same purposes also 
have about the same manganese content, and some a good bit higher. 

A Peculiar Non-Tungsten Steel. — In Europe, more especially in France, 
there are coming into use semi-high-speed steels of the approximate 
composition: 

Per cent. 

Carbon 2 . 25 

Chromium 15 . 00 

Manganese . 85 

They differ very greatly from the steels constituted according to the 
now accepted ideas, not only in the absence of tungsten or molybdenum, 
but in the very high chromium and carbon. This accounts for the 
exceeding difficulty with which they are worked. As a compensation 
for this however, they require a hardening temperature of but 900 de- 
grees C. (or 1,650 F.). They are stated to be but slightly inferior to 
regular high-speed steels in point of service. 

Recent Developments. — The most recent development in high-speed 
steels is the announcement and marketing of what have been variously 
designated the " new," " improved," " superior," and the like, high- 
speed steels. Astonishing claims have been set forth by makers and 
others, for these " new " steels. Speeds of two or three, to ten times 
those attainable with " ordinary " high-speed tools, have been asserted 
to be possible; and an endurance many times as great has been claimed. 
And all this with a steel which could be hardened in water! 

The "New" Steels — Claims. — Tests have not been wanting whose 
results seem to lend support to the claims made, and the performances 
of tools made of the steels (mostly English) thus advertised have been 



52 HIGHSPEED STEEL 

very good indeed. A cutting speed of 500 feet per minute under proper 
conditions is said to have been attained, while speeds greatly in excess of 
those usual with ordinary high-speed tools have been claimed. The claim 
of superiority in cutting speeds has however been usually subordinated 
to that of greatly increased endurance, especially in cutting materials 
exceptionally refractory. Thus chilled iron, which can be cut only with 
some difficulty by ordinary high-speed tools, at speeds usually under 
ten feet per minute, and then only with very frequent grindings of the 
tools, have been machined with comparative ease. Hard spots in such 
work as tire turning, say, present little obstacle to these tools. Grindings 
can be reduced by a half at least, and, in cases, may be almost eliminated. 
Such are the claims put forth. 

There can be no question of the extraordinary powers of the steels, 
offered under the new names. Many of the claims made, however, 
relative to their superiority over " ordinary " high-speed steel, have 
evidently been based on comparisons with very " ordinary " high-speed 
steels, or with tools differently treated. As a matter of fact there have 
been a number of high-speed steels upon the market for several years, 
sold under the regular names and at no increase in price, which under 
similar conditions have easily equalled, and in some cases exceeded, any 
reported performance of the so-called " new " steels. Side by side, on 
regular work, with the same treatment, it has not yet been shown con- 
clusively that the "new" steels are in any respect superior to any one 
of several American brands whose composition has been practically 
unchanged for several years. 

" New " and " Ordinary " Steels Compared. — The fact is, it is very 
unusual indeed for any tool to be worked to its limit, especially in regular 
shop practice; and a tool easily capable of running at two or three hun- 
dred feet per minute, for reasons well understood, rarely is run half as fast. 
Furthermore, it is common practice, and good practice too, for tools to be 
ground more frequently than is absolutely necessary so far as metal- 
removing capability is concerned. There have indeed been occasional 
" tests " to show what could be done. The limitations affecting regular 
work however have in general served to prevent the adoption of the higher 
limits of possibilities, even when these have been ascertained. A series 
of experiments carried on since the announcement of the " new " steels, 
for example, with a machine designed especially for the experiments and 
with a view to reaching the limit of performance, proved only that the 
limit of speed could not be reached on that machine. A speed of more 
than 200 feet per minute, rough turning cast iron, was maintained easily. 
In another instance a different tool showed itself capable of standing up all 
day under a speed of 130 to 140 feet per minute while taking a cut T f inch 
deep and with a feed varying from |- to \ inch. No " new " high-speed 
steel seems to have excelled this performance, or apparently equalled it. 



STILL NEWER STEELS 53 

Water Hardening. — The performance first mentioned was with a tool 
whose point had been hardened by dipping in cool water and then 
quenching all over in oil, the temper being afterward slightly drawn. 
A tool so treated would of course be exceedingly hard. To get the 
astonishing results claimed for the " new " steels, that is, results aston- 
ishing when compared with customary performances, the water treat- 
ment is likewise necessary. At first there was a disposition to attach 
much importance to the possibility of hardening in water, and it has 
been stated that a tool of a " new " high-speed steel has been successively 
hardened in this manner a great many times without cracking. There 
would be nothing remarkable in this, especially if the tool contained 
vanadium, as probably it did. Other high-speed tools also have been 
hardened in water and made glassy hard. But it is not safe to harden 
any high-speed steel in this manner, whether of the so-called "new" 
or of the " ordinary " kind. A tool might be successfully hardened in 
this manner a dozen times — and again, it might crack the first time. 
There is no way of knowing beforehand. It is for this reason that the 
caution is often repeated in this book, not only to avoid water in hard- 
ening high-speed tools, but to keep it entirely away from tools either hot 
or liable to be heated. It is not singular, under the circumstances, 
that the makers of the " new " steels declare for the customary method 
of hardening in air or in oil. 

Nature of the "New" Steels. — The "new" steels unquestionably 
are good steels, and superior to most, though not all others previously 
on the market. What superiority they possess over ordinary steels is 
doubtless due in large part to the increased percentage of alloy, com- 
pared with the low proportion generally found in English and continental 
brands, and in part, very likely, to the. presence of such elements as 
titanium and vanadium, up to this time little used in 'ordinary high- 
speed steels. It is noteworthy, however, that one of the very best of 
the standard high-speed steels (an example of whose performance is 
mentioned above) rarely yields vanadium upon analysis. The treat- 
ment requisite for the " new " steels is essentially the same as for other 
good high-speed steels. In some cases a rather higher forging heat is 
recommended. 



54 



HIGH-SPEED STEEL 




CHAPTER V. 

THE PROCESS OF MAKING HIGH-SPEED STEELS. 

The Crucible Process. — Mention has been already made of the three 
processes for making steel, namely crucible, open hearth, and bessemer. 
Of these only the crucible process produces steel suitable, generally 
speaking, for use in tools, and especially in cutting tools. It is by this 
process only that high-speed steel was produced until recently. The 




Fig. 40. The furnaces (tops at the floor level) and the crucible pits. 

electrical furnace, with its very high quality of product, now is also used 
to some extent. 

The crucible process, the simplest of those in use, is centuries old, 
reaching back to those days in the misty past into which history has not 
penetrated. The modern method of producing crucible steel is essen- 
tially the same as that by which wootz was made; but of course in its 
details it has been greatly improved. And though it is the simplest of 
the three processes now in use, it is by far the most costly. Briefly it 

55 



56 HIGH-SPEED STEEL 

consists in placing together in a clay or graphite crucible, the iron and 
charcoal, wood, or other substances which are to enter into or affect the 
final product; setting the crucible in a furnace and melting its contents; 
and afterwards " working " the product to secure density and form. 

Charging the Crucibles. — Crucibles, as used in steel making in this 
country, are usually made of a mixture of 50 per cent graphite and 50 per 
cent clay. In Europe all clay crucibles are quite generally used. The 
latter have certain advantages, but are much less durable than those com- 
posed largely of graphite. The charge rarely exceeds 125 pounds, and is 
only 50 pounds when clay crucibles are used. The amount of iron, char- 
coal (to furnish carbon), tungsten, molybdenum, or whatever other agent 
or combination of agents is demanded by the formula, is exactly measured 
in the " mixing room," and this formula once adopted as the result of 
much experiment, is religiously followed, in order to preserve as close 
uniformity in the product as possible. 

The hardening agents are preferably placed at the ' bottom of the 
crucible, and the small pieces of iron carefully packed over them. The 
crucible is then lowered into the melting hole and a cover placed over 
it to keep out gases, and the melting hole itself carefully sealed up. 

Melting — Furnaces and Methods. — The method of placing the crucible 
in the melting hole, and removing it has changed little since early times. 
The melter, or more often his helper (sometimes called " puller out ") 
grasps the filled crucible with tongs shaped to fit its sides, and straddling 
the hole, lowers until the crucible rests upon the floor of the hole or upon 
a suitable bed of fuel, as the case may be. In like manner the crucible is 
" pulled " after the melt is ready for pouring. 

Obviously this is very hot work. Indeed it is customary for the 
"puller out " to swathe his legs in wet cloths to avoid being scorched; 
and even then he not infrequently catches fire and has to extinguish 
himself. In a very few modern plants, especially where large quantities 
of metal are made, mechanical methods of handling are employed, 
generally an overhead trolley hoist operating the tongs. 

The melting hole usually is one of several, perhaps as many as twenty. 
Commonly each hole accommodates four to six crucibles; and generally all 
are connected with the same main flue and stack, though in other respects 
each is practically a separate furnace. Where gas is used for heating, 
the furnace is of the reverberatory kind, with regenerators and checkers; 
and is provided with suitable valves and dampers for regulating the 
temperature. For high-speed steel melting this type is most satisfac- 
tory because of the ease with which the temperature can be maintained 
at a very high point and also kept uniform for any desired time. 

In some cases the melting is done in an ordinary coke hole, also pro- . 
vided with drafts and dampers for controlling the temperature. The 
hole is pretty well filled with coke or anthracite piled around the crucibles, 



THE PROCESS OF MAKING HIGH-SPEED STEELS 57 




Fig. 41. The stalwart melters. 




Fig. 42. "Pulling" the crucible. 



58 



HIGH-SPEED STEEL 



and the heat gradually brought up to the high temperature necessary, 
and maintained as long as may be required, care being taken to replenish 
the fuel from time to time. 

Ordinary crucible steel melts in 2 to 4 hours, and rarely requires 
more than 3 hours, if the stock is not in too large pieces and the furnace 
is kept well regulated. High-speed steel however requires much longer. 
For those steels containing manganese 8 hours is not unusual; and for 
the very best grades of high-speed steel the melting may require as much 
as 10 hours, and even more, though usually 4 to 5 hours is sufficient. 
The melter's experience is his chief guide in determining when the meUing 
is complete, and then the melting hole and crucible are opened for 
examination. For the most part the melter depends upon his eye to 
determine the progress of the melt, and if he makes a mistake it may be 
at total loss. 

Killing or Dead Melting. — In all crucible steel manufacture the " teem- 
ing " or emptying of the crucible is not done immediately after the melt 




Fig. 43. Teeming or Pouring. 



has become sufficiently fluid; but is deferred for a time (rarely up to 
two or three hours, usually 30 minutes) while it is being " killed " or 
" dead melted." This consists merely in allowing the crucible and its 
contents to remain in the melting hole until the liquid steel has become 
quiescent and is in such condition that when teemed the resulting ingot 
will probably be sound, that is, free from blow holes. Killing has an 
important effect upon the density and uniformity of the steel, due, it is 



THE PROCESS OF MAKING HIGH-SPEED STEELS 59 

thought, to the escape of certain ^^ f^l^Z* 
The operation is longer or shorter ^' n ^ c Zu\ni the melting 

slow. The time c epe * ^ twenty ^ 

t'Tn hoirthe y eye o he -1^ a g L determining when the melt is 
dv There can not, in the nature of the case, be any sharp hue of 
ready. Ineie can noL, combined opera- 

demarkation between melting and killing, tor trie w 

molds. If the metal Decom ldg are customarl ly small 

the -nltmg mgo > .hkely *£ **^ and are very deep in proportion 
,n section, raiely exceeding 4 y ^ together by 

t0 t^ir cross secrtonUualy they « ^ ^ . 

t'olv^he ingot S surface and prevent its sticking to the sides of 

th T^mL -The slag having been skimmed off, the teemer quickly 
JpTs'the Juelbfelnto th/mold in pre^dy the ^manner - is 
done in teeming »^ «* g J^TstiU to teem properly, 

of the mold. The stream must not at any time in 

TnlY moMs'used in the manufacture of high-speed steel usually 

Ingot molds useam oruci ble though sometimes larger ones 

hold the contents of but a single crucible, inoj * DurD0Ses In this 

having been mixed in a ladle. the mold 

is ^o^o "^ed" S-f£ -pV Loken off, to remove the 
pipedTdsegregated P portion likely to be our ^^J^™ 
face of the remaining portion^ ^^f^ ^ out . At 
and such minor superficial ones as are msc satisfactory, 

the same time a sample ^ " ^nt IT — Ahe rejection 
and no physical detect Being iounu v,»«tinir not infrequently 

and remelting of the ingot, after a prolong^ heating not n q y 

lasting two days (for the ingots having been in chil m ,^ 

intensely hard) at a temperature close to » <"• P in 

the hammer and thoroughly worked out mto » rollg for 

thoroughly inspected, and if pert ect go * theb«nm» hammered 
finishing to the require [section _ Most high spe hamm6ring and 

nearly to shape, and then rolled to a nmsn. 



60 



HIGH-SPEED STEEL 




Fig. 44. Billets ooming from the shears. 




Fig. 45. Forging out the bars under the steam hammer. 



THE PROCESS OF MAKING HIGH-SPEED STEELS 61 

rolling must be done at a heat considerably higher than that used in the 
case of ordinary steels. These alloy steels are so dense that they work 
well only when at a bright red or even higher temperature. If ham- 
mered or rojled at a lower temperature the metal does not flow freely 
and uniformly under the blows or pressure, and strains, if not cracks, are 
caused — generally bad cracks, which unfit the steel for its special use. 
Even if no cracks develop immediately, the strains thus set up, unless 
let down by subsequent thorough annealing, frequently produce cracks 
and failures long after the bars have been passed as perfect, and more 
than likely after they have been put to use. To insure freedom from 
defects the forging temperature is customarily near 1,000 degrees C. 
(1850 F.). 

Annealing. — High-speed steel being partially self-hardening, the bars 
when finished are hard and require annealing except for a very few 
purposes. Unless annealed the bars cannot well be used even when 
they only require to be ground and inserted in a holder, owing to the" 
difficulty of breaking off what may be wanted; and it is utterly impos- 
sible to machine high-speed steel in this condition into any of the many 
special forms required. The hard bars can of course be forged; but 
even in this case it is much better to use annealed stock, for several rea- 
sons, the most important of which is that annealing relieves the internal 
•strains set up in hammering or rolling and decreases the liability to 
future flaws or cracks. Also, the structure of the steel becomes uniform, 
homogeneous, and tenacious; and according to the testimony of some, 
its life is increased. 

The annealing is done in muffle ovens of the customary type, the heat 
being gradually brought up to a red heat of 800 degrees C. (1500 F.) or 
somewhat higher. The bars may then be removed and slowly cooled, 
but much better results are obtained when they are allowed to cool in the 
oven itself, the heat being shut off soon after the desired temperature 
has been reached, and the oven allowed to cool slowly. As in the 
other processes, great care must be taken that conditions are just right, 
else there is likelihood of the steel coming out poor or indifferent in 
quality, even when the mixture is good. Twelve to eighteen hours, 
according to the size and shape of the bars, is required for proper 
annealing. 

Refinement of Methods. — Those familiar with the process of making 
ordinary crucible steel doubtless will have noted already that the process 
of making high-speed steel differs from it in few important respects. 
In general the equipment used and the methods practiced are identical. 
The chief difference is in the stock put into the crucible, and in the 
exceeding care exercised throughout in producing the high-speed steel. 
In a mill which endeavors to make and keep up a reputation for pro- 
ducing a superior quality of high-speed steel, the extent and frequency 



62 HIGH-SPEED STEEL 

of the examinations and tests of stock in process of manufacture, is 
surprising. The ingots are carefully analysed, and are inspected be- 
fore as well as after " topping." The topping itself is intended to 
remove any possible inferior metal or defects, frequently found in that 
portion of the ingot. The billet is again inspected; and each separate 
bar likewise undergoes examination for defects. The bars are generally 
"pickled" to make defects more easily discernible, if any exist. If 
defects appear at any time in the course of all these inspections, the 
material is rejected if inferior in quality, or re-melted if merely defective 
in structure. 

Considering the care necessary in its manufacture, and the high skill 
required in the workmen, it is not at all singular that high-speed steel 
continues to sell at the extraordinarily high price which it commands 
in the market. There are, however, additional reasons for its high 
price, chief among which is the high cost of the special alloying 
elements. 

Kind and Quality of Constituent Materials. — The materials used are 
necessarily of the purest, and certain of them are rare; for both of 
which reasons their cost is very high. Some makers use only the purest 
Swedish and Dannemora iron, saying that these alone are free enough 
from sulphur, phosphorus, and other impurities, to give the best results 
in high-speed steel. These irons are considerably more costly than 
even the best of ordinary kinds. A number of makers however, utilize 
good qualities of native muck bar, saying that these give results as 
good as can be obtained; but these extra pure irons also have a higher 
price than the ordinary. The tungsten, molybdenum, and other hard- 
ening metals, vanadium especially, are rare, their ores being found 
in but few places and those usually not easily accessible. These ores 
are commonly reduced in the electric furnace, sometimes to the metal- 
lic state, and at others to the ferro alloys, either of which can be used 
in the manufacture of high-speed steel. The prices of these metals range, 
in either state, from $0. 40 to $7.00 per pound. 1 Since the proportion of 

1 The prices quoted in March, 1908, were approximately as follows: 

Tungsten $0 . 75 per lb. 

Vanadium 6 . 00 " 

Molybdenum 1 . 50 " 

Titanium 1 . 00 " 

Chromium 37J to .75 " 

The figures given are for the contained metal in the ferro state. Swedish iron was 
at the same time quoted at about three cents per pound. 

Ten years before these metals were stated to be worth a great deal more, as may 
be seen from this quotation taken from the columns of a scientific paper of the time: 

Tungsten $36 .00 per lb. 

Vanadium 10,780 .00 " 

Molybdenum 245.00 " 

Titanium 1,100.00 " 

Chromium 490.00 " 



THE PROCESS OF MAKING HIGH-SPEED STEELS 63 

hardening metals is not infrequently above 20 per cent, it is seen that 
the cost of material alone is something quite different from what it is 
in the case of ordinary steels. 

Possible towered Cost. — In spite of the keen competition among 
makers, the price of high-speed steel has remained, practically where it 
was when first put upon the market, for the best grades not far from 
SO. 70 per pound, in small quantities. The so-called "new" steels 
sell for considerably more. This seems altogether out of proportion,' 
at first thought, even when the high cost of manufacture is considered. 
It is to be remembered, however, that this includes the as yet high cost 
of marketing; and must, of course, cover in part, also, the great expense 
of continued experimentation necessary to determine the most desirable 
composition and method of production. The cost of certain of the 
hardening constituents has increased considerably of late, owing to the 
large demand; but it may be expected that new sources of supply will 
be located and the methods of extracting the metals and ferro alloys 
will be so simplified that this cost will be materially reduced. It is 
becoming known, also, that the more rare of these agents are by no 
means essential to a good grade of high-speed steel; for other and less 
costly ones can be combined so as to give satisfactory results, especi- 
ally for that intermediate class of tools of which the highest duty is 
neither required nor desired. Apparently the marketing of the new 
steels is as yet one of the most costly items to the makers. As the 
place of the new tools becomes more and more definitely established 
the cost of bringing it to the attention of users will of course decrease, 
and the total cost to the consumer will without doubt be more nearly 
commensurate with what would be expected, and the economic value 
of the new steels be correspondingly increased. 



CHAPTER VI 

FORGING THE TOOLS. 

Stinted Use of High-Speed Tools. — The demonstrated utility and all- 
round superiority of high-speed steel for tools in most lines of metal 
working, and in other lines also, would lead to the inference that they 
are used to the largest possible extent. A recent study of machine shop 
conditions has shown conclusively that while they have taken a very 
large place in productive industry, the new tools are not used to any- 
thing like the extent they might be with profit. In comparatively 
few shops is high-speed steel largely used; in most, to a very moderate 
extent only; while in a great many it is quite unknown. 

Unsatisfactory Experiences. — Conservatism of course plays a large 
part in this condition of affairs, while unfortunate and misleading 
experiences seem to be responsible for the indifferent or negative atti- 
tude in many quarters. That there have been unfortunate and mis- 
leading experiences is for the most part due to the unintelligent manner 
in which the new problems of using high-speed tools is generally at- 
tacked. Persuaded in one way or another to buy some high-speed 
steel, the management of a shop more than likely turns the stock over 
to the regular tool makers, who are in this case almost sure to be unfamil- 
iar with its properties and the methods of treating it — and more than 
likely also, prejudiced against such new-fangled stuff. Under these 
circumstances it is not surprising that tool makers so often fail to profit 
to the largest extent by the directions furnished with the steel. Even 
when these necessarily brief and incomplete directions are followed 
as faithfully as possible, the inexperience of the smith makes his efforts 
more or less experimental, and the results may or may not be satisfactory. 

Purchasing Tools to Specifications. — The obvious thing to do, as 
pointed out in another place, is to buy tools made to specifications, 
for such introductory experiments. This also is the proper procedure 
in small shops using few special tools, after they have gone into regular 
use. Makers are quite ready to furnish tools of any pattern to specifi- 
cations designating precisely the material upon which they are to work 
and the machine and other conditions under which they are to operate. 
In this way there can be little question of the results being satisfactory. 

Making Simple Tools. — The making of the common forms of lathe and 
planer tools is so simple a thing however that it can be undertaken 

64 



FORGING THE TOOLS 65 

in almost any shop having tool-dressing facilities — provided the smith 
is willing to forget, for the time being, some of the things he already 
knows concerning carbon steels, and also to learn a few things which may 
be quite surprising to him, particulary if he has no experience with 
high-speed steel. His knowledge of colors, as a guide to heating and 
tempering tools, for instance, will be no guide at all, and is likely only to 
mislead him. 

Whether it be in a large or a small plant, unless the work is in the hands 
of a trained expert, the first experiences in the making of high-speed 
tools should be with the simpler forms already indicated. These usually 
require little in the way of special appliances in order to give fairly satis- 
factory results. In their making, nevertheless, is involved the same 
special knowledge as to treatment which is necessary in the case of more 
complex tools. 

Use of Tool-Holder Stock. — Formerly it was a common practice to use 
high-speed lathe tools in connection with tool holders, merely breaking 
off from the bar a piece of the desired length, grinding it to the required 
point, and inserting it in the holder. This is still largely done where the 
work is light and the speeds not intended to be very high. The unan- 
nealed stock was once quite generally used for the purpose. This stock, 
however, while very hard, has not (in the case of most brands, at any 
rate) passed through a proper hardening process, having acquired its 
hardness while cooling under the stresses of the rolls or blows of the 
hammers. To insure an even temper and the absence of strains which 
tend to imperfections and therefore short service, it is necessary to 
anneal the tool pieces, and then to harden them properly. For this 
reason, as well as for greater ease in separating the desired piece from 
the bar, the annealed stock should be used, thus avoiding the annealing 
process in making the tool. 

Cutting Stock from Bars. — High-speed steel bars which have been so 
annealed can be easily nicked and broken off, unless of large section. In 
that case it takes an expert to do it. Breaking however is not advisable, 
for it is likely to cause a disarrangement of the structure of the steel 
near the fracture, sufficient to damage the tool at that place. Frequently 
fine cracks are started which later develop, and eventually spoil the tool. 
It is safer, and when the nose of the tool is to be forged any way, causes 
no additional labor, to heat and cut off hot. In general also it is more 
convenient to forge tools of this sort before cutting from the bar. Where 
many pieces are used, especially if little or no forging is required, whether 
of the same or different lengths, it is cheaper to saw them off to length by 
a power saw. It is unnecessary to do this one at a time, for if clamped 
tightly enough and sawed close to the support, a large bunch of " tool 
holder " stock, for example, can be sawed through as if it were a solid 
bar. As between a band and a circular saw, the former is preferred. 



66 



HIGH-SPEED STEEL 



Most such cutting can be avoided by purchasing tool-holder stock ready 
cut to desired lengths. 

Advantages of Annealed Stock. — In making tools requiring more or 
less machining there is an additional advantage in the use of the annealed 
stock, in that it is readily machined — almost if not quite as easily as 
carbon steel used for the same purposes. In some kinds of tools this is 
of considerable importance. Again, the annealed stock is stronger, that 
is to say, tougher; and tools made from it are therefore better able to 

resist stresses in the neck or shank 
than if made of the unannealed, and 
on that account are less liable to 
breakage at those points. The tre- 
mendous stresses and strains accom- 
panying the use of these tools makes 
it important to look to this matter. 
The early complaints against uneven- 
ness have almost wholly ceased since 
makers, mindful of their own inter- 
ests as well as of the interests of the 
users cf their steels, have made a 
practice of sending out annealed bars 
only, except upon special order. 

The Forge Fire. — For forging, any 
good fire, a common forge fire among 
the rest, will serve; though indeed 
here, as in other cases, the better 
results can be expected where the 
better appliances are used. The first 
essentials are to secure the required 
heat and to keep air currents away 
from the tool while heating. This is 
accomplished in part by keeping a 
deep and clean fire. Coke is better 
than the ordinary smith's soft coal, 
the latter having a tendency to burn 
out too rapidly. Very good results 
are occasionally obtained in this way, 
though they cannot be expected as a regular thing. If a forge fire must 
be used, a hood of fire brick should be laid up over the fire to prevent 
radiation and the circulation of air currents. This hood makes it some- 
what easier to conform to another prime essential in forging high-speed 
steel, namely, that the piece be brought up to the forging heat gradually 
so the heat penetrates uniformly to the very center. This is exceedingly 
important and will be mentioned again. 




Fig. 46. Good type of ,gas forge. Made by 
the American Gas Furnace Co., New York. 



FORGING THE TOOLS 



67 



Advantage of Good Equipment. — Although it is possible, as has just 
been said^ to obtain good results with very primitive appliances, it does 
not pay to try to get along without suitable apparatus if even a few 
high-speed tools are regularly produced. These tools are of no especial 
value above ordinary ones unless they are made uniform and exactly to 
the specifications requisite for the various special duties to which they 
are set; and it is the height of folly to spend good money for tools 
indifferently made. Especially where many tools are requried, suitably 
designed furnaces and other appliances are absolutely essential to the 
obtaining of satisfactory results. 

Convenience of Gas Furnace — Coke Fire. — For forging, a gas furnace 
is unquestionably the most convenient; and in the long run it is prob- 
ably as economical as any other. Some users maintain it is more so, 
in the matter of fuel cost, maintenance and tool output. However that 
may be, the coke furnace, when properly designed, is very satisfactory 
and efficient. 

The gas forge has much to recommend it — convenience, cleanliness, 
minimum attention to operation and maintenance, ease of regulation, 
and uniformity of results, among other things. Customarily of the oven 
type, it is provided, as is the case with 
gas-hardening furnaces also, with air 
under slight pressure, say one to two 
pounds, and suitable means for control- 
ling the flow of air and gas and for 
properly mixing them in order to insure 
perfect combustion and economy of gas 
consumption. 

A Good Coke Furnace. — The coke fur- 
nace is much used, both for forging and 
hardening. Where the amount of work 
done is comparatively small, the same 
furnace will answer for both purposes, 
as also will the gas forge. A good form, 
easily built and as easily operated and 
maintained, is illustrated herewith, Fig. 
47. Essentially it consists of a sheet 
metal or cast jacket enclosing the fire-brick heating chamber. Sheet 
metal fuel hoppers are at each side, so placed that the supply of coke 
or anthracite (either may be used, if in small lumps) is continuous and 
is fed directly to the top of the fire bed. The result is a hollow fire of 
uniform temperature, the fuel being gradually heated in its descent, to 
the temperature of the deep fire bed. The latter, filling the chamber 
to the fore plate, or perhaps slightly above, rests upon a sectional grate 
of cast iron, preferably arranged so as to be rocked when shaking down 




Fig. 47. _ A simple coke furnace adapted 
to either forging or hardening. 



68 HIGH-SPEED STEEL 

ashes. The ash pit is also a wind box, whence air under slight pressure 
from the blower is forced up through the fire. The temperature is 
regulated to a nicety by the damper in the exhaust and the cut-off in the 
air supply pipe, and that with almost no attention. When not in use, 
the fuel is conserved by entirely shutting off the drafts, the amount 
consumed then becoming negligible. As the gases from a coke fire are 
almost or wholly non-oxidizing, a tool is not likely to be injured when 
heated in this way. An important advantage possessed by this form of 
coke furnace is that the heat is almost wholly confined to the fire cham- 
ber, so that there is no waste of fuel, or discomfort for the operator. 

Gradual Heating Necessary. — The heating proceeds at a moderate 
rate, neither too rapidly nor too slowly. In the former case the heat 
does not penetrate uniformly to the center and in the forging the steel 
does not flow freely under the blows of the hammer, with the results 
hereafter pointed out. There is danger also that cracks will be formed 
because of the strains set up through the unequal expansion of exterior 
and interior.- If the heating goes on very slowly the heat soaks up into 
the neck or shank of the tool, and when hardening takes place, unless 
the tool is annealed before that operation, this part has lost much of its 
natural toughness — a thing to be avoided, as already pointed out. 
In the case of unannealecl stock, which is hard anyway, the slow heating 
is of less consequence. The fire therefore must be clean and well sup- 
ported by good fuel in the case of a coke furnace, and well regulated 
in that of the gas furnace. In all cases it must not be too keen, for 
then the outer parts of the tool are almost certain to become very hot 
before the interior reaches a forging heat, that is to say, at least a bright 
red. It is of course, impossible to know precisely the interior condition 
of a heated piece of steel in ordinary practical operations, so that the 
smith must be guided very largely by his experience and judgment as 
to the proper time during which a particular tool is to be heated. It 
is safe to assume, in general, that a piece having a section not greater 
than one inch, if properly protected, or if heated in a good gas or coke 
furnace as already described, will be ready for forging when the exterior 
has reached a bright yellow. 

Effect of Uneven Heating. — No hammering should be done under any 
circumstances while the portion of a tool that is being forged is under 
a good red heat. Neither should the interior be considerably hotter" 
than the exterior, as is likely to be the case when the tool is large and 
forged on a cold anvil. The disregard of these cautions is almost certain to 
result in defective tools. The consequence is shown in the accompanying 
Figures 48 and 49. When forged with the center much hotter than 
the outside, the former remaining expanded to a greater degree than 
the latter when the forging is finished, contracts on cooling, with the 
result that there are minute openings within, while the outside appears 



FORGING THE TOOLS 



69 



F 



perfectly sound (Fig. 48). If, on the other hand, the outside be flowing 
freely while the interior is still too cold to forge readily, the outer 
portion on coojing contracts over the 
hard inside and in consequence there 
are likely to be many fine cracks on 
the surface, as shown in Fig. 49. Not 
infrequently these defects are not evi- 
dent, and make themselves known 
later, during the grinding or machin- 
ing (in the case of tools requiring 
this), or more likely during the hard- 
ening. Sometimes the damage does 
not manifest itself until the tool is set 



Fig. 48. What is likely to take place when 
the interior of a tool being forged is 
much hotter than the exterior. 



X^ 



rr ' 1 1 



^Kx 




r 



Fig. 49. Result likely to occur when forging 
with exterior of tool much hotter than 
interior portions. 

to its work, possibly not until 
sometime after, when greatly to 
the surprise of the user it sud- 
denly fails without apparent 
MjjLjsm cause. 

I Forging Temperature. — It is 

} '"::.,,.._, """--\ better to do all forging at an 

orange or even a canary yellow 
than below that temperature, for 
it in large measure obviates the 
danger of imperfect working just 
pointed out. High-speed steel is 
difficult enough to forge anyway, 
considerably more so than ordi- 
nary steels, though less so than 
the self-hardening steels; and it 
is well to keep it as ductile as 
possible. The various makers of 
these steels generally give very 
brief directions as to the forging 
heats to be employed, in a number 
| of cases indicating that a good 
red is high enough. In general it 
may be said that while this is 
usually high enough, the reasons 
already stated are sufficient to 
make the higher forging heat desirable in practically all cases. Even in 
the case of inferior high-speed steel the forging heat must be high enough 




Fig. 50. Heel of tool being drawn down under steam 
hammer to give support to the nose almost di- 
rectly beneath the cutting edge. A power ham- 
mer allows rapid forging of large tools and is on 
that account very desirable. 



70 



HIGH-SPEED STEEL 



so that there is no metallic ring under the hammer, only a dull sound. 
The temperature range recommended is something like a hundred or a 
hundred and fifty degrees from and above 1,000 degrees C, or from 
about 1,850 to nearly 2,250 F. Precise temperatures are, in forging, 
not a matter of particular concern, the colors being sufficient guide if 
care be taken to keep the temperature of the interior and of the exterior 
approximately uniform and well above the minimum bright red already 
suggested. 

Cautions as to Hammering. — The proper heat having been obtained, 
the forging is done in the customary manner. Inasmuch however, as 




Fig. 51. Tool bent down across edge of the anvil ("turned up"). 



high-speed steel works somewhat harder than ordinary steels, it is neces- 
sary to exercise some discretion with respect to the force of the blows. 
Indiscriminate hammering is likely to prove ruinous. A large piece 
needs to have the blows heavy enough so that their force sinks into 
the interior instead of being absorbed at the surface alone. On the 
other hand, a light tool would be ruined by heavy blows unsuited to 
its size. 

It is important also that the forging be done rapidly, so as to be 
completed in one heat if possible. This helps to avoid the troubles 
just described. Tools requiring considerable working, as in the case 
of the Taylor standard lathe tools, for example, generally require at 



FORGING THE TOOLS 



71 



least two, and sometimes three heats, according to the tool and the 
number of helpers or the use or nonuse of a power hammer. The 
latter not only saves labor, but is likely, especially in the case of heavy 
tools, to add considerably to the excellence of the forging. 

Successive Steps in Forging. — Concerning the successive steps in the 
forming of a tool, and the special methods to be employed, it would 




Fig. 52. Forming a bent side tool. 



seem scarcely necessary to say much. The steps are practically the 
same as those in the making of a tool from ordinary steel, and the 
methods may be about the same also, except that it is well to take into 
consideration the fact that the tungsten steels forge with greater diffi- 
culty than carbon steels do, and that in bending and similar work it 
is desirable to resort to certain expedients for facilitating the work, 
as shown in the accompanying illustrations, Figures 51 to 56 inclu- 



72 



HIGH-SPEED STEEL 



sive, 1 some of which show the methods recommended by Mr. Taylor. 
The clamp attachment for the anvil, shown in Figure 51 is of partic- 
ular interest. Its application will be readily understood from the 
illustration. 




Fig. 53. Forming a side roughing tool. 

Close vs. Rough Forging — Gages. — It is well to shape the tool as closely 
to the required form and dimensions as possible without over refine- 
ment, in order to save grinding. Of course there is an economic limit 
to the closeness of the forging, for when this approaches refinement, it 
is cheaper to grind. It is desirable to use gages freely for testing the 
form and size of tools as the work progresses. In some cases forms' 
have been used in connection with the anvil (Fig. 55), in which the 
shapes are forged with precision bu<", without great expenditure of time. 



1 Figures 50, 51, 54, 56, 57 and a number of others throughout this book, are 
taken from Mr. Taylor's Address. Figures 52, 55, and several others also, are used 
through the courtesy of the Gisholt Machine Company. 



FORGING THE TOOLS 



73 



Customarily a combination gage, giving all the required angles of a 
particular tool, will be sufficient. Mr. Taylor, in his report already 
mentioned, describes and illustrates along with others, a surface plate 
and cone gage, here shown in Fig. 56. The plate has a hole in one 
corner, into which fit the dowels of various cones giving the desired 
angles. The limits gage, intended to be used in the making of the 
Taylor standard lathe tools, also is illustrated, at Fig. 57. This indi- 
cates the extreme limits within which the forging must be done. The 
limits may vary in different shops according to the adequacy or in- 
adequacy of the grinding facilities. The cheaper the grinding cost, 
the less accurate of course may be the forging. 




Fig. 54. Successive stages of forged and ground tools. Courtesy of Machinery. 



A very simple and convenient gage, Fig. 58, which, however, does 
not give precisely the actual lip slope, consists of a small piece of sheet 
metal giving all the angles of a particular tool. A surface plate is almost 
essential in connection with this gage. Not quite so simple, but very 
convenient, is the gage shown in Fig. 59. This resembles somewhat 
the Taylor limits gage, but gives only the minor limit of the nose form. 
In addition it gives, as the Taylor gage also might be made to give, 
all the other angles required. Of course, a set of gages is required, 
one for each tool made in quantities sufficient to warrant the expense. 



74 



HIGH-SPEED STEEL 




Fig. 55. A set of forming blocks to be used in forging lathe tools, furnished by Gisholt Machine Company 
with their tool grinder and form chart. 




Fia. 56. Trying tool against cone gage to test proper angle for nose. 



FORGING THE TOOLS 



75 



Form gages should provide for an allowance of T \ to I inch which is 
to be ground off the working edge of the tool. Even when gages are 
deemed unnecessary, this allowance is to be made by the smith; other- 




Fig. 57. Limit gage for forging the 1-inch Taylor round-nose roughing tools. 





Fig. 58. Simple gage used for testing angles of English form of blunt-nose tool. 
Courtesy of Samuel Osborn & Co., Ltd. 

wise the amount ground off will not be sufficient to remove all the 
burnt metal, and the tool will in that case work at a low efficiency 
until it has had several grindings. Many have noticed that, in their 



76 



HIGH-SPEED STEEL 



own experience, tools seemed to improve with use, at least for some 
time after being set at work, particularly if the grinclings were light. 
That is, after each grinding the tool seemed to last longer than before. 
Of course this is exactly what would be expected to happen when the 
tool has been insufficiently ground the first time. Each grinding 
removes more of the somewhat burnt outside portion, until the unin- 
jured metal is reached and the tool works at its highest efficiency. 




Fig. 59. Simple gage for standard roughing tool. 



Need for True Tool Bases. — It must be remembered that the tools 
now under consideration, mostly lathe and similar forms, are subjected 
to tremendous strains, and that they must on that account be held 
very firmly in position. For this reason, it is necessary that the side 
upon which such a tool rests in the post or holder shall be smooth and 
true, so that it shall be firmly supported. After hammering true on 
the anvil it is well also to grind the base. 

Guarding Against Strains — Re-annealing. — If reasonable care has been 
exercised during the forging it is unlikely that strains will have been 
set up. It is well, nevertheless, to guard against the possibility of 
them by re-heating tools to a bright red, holding them at this heat 
for a short time, and then allowing them to cool slowly in air or in dry 
ashes. This is to be done before the hardening, and after the forging 
heat has gone down below a black. The partial annealing not only 
helps to remove possible strains, but softens tools so that they can be 



FORGING THE TOOLS 77 

ground with ease to their approximate shapes, or machined without 
difficulty, should this operation be necessary. It likewise anneals the 
neck or shank of a tool when this has for any reason been allowed to 
reach a high heat during the forging of the cutting portion. 

Grinding off Excess Metal. — Excess of metal, beyond what is neces- 
sarily removed after hardening for reasons previously given, is best 
ground off immediately after forging or annealing as above, on a dry 
emery wheel. This may be done while the tool is still red hot, or at 
any subsequent time before hardening. 

Danger in Stamping High-Speed Tools. — Attention has been directed 
to the possible results attending nicking and breaking off tools from 
the bar stock. It is unwise also to make any nicks or marks on a high- 
speed steel tool at any place where stresses are applied. All stampings 
or other marks, such as are customarily made for identification, should 
be put in places where cracks can do no harm. A mark or nick in 
high-speed steel acts very much as does a diamond scratch in a sheet 
of glass, and will, in a part of the tool subject to strains, often eventu- 
ate in its ruin. Even when placed where no harm apparently can come, 
it is advisable that the marks be no deeper than necessary to serve 
their purpose. 

Forging vs. Machining Tools. — It may be well to observe here that 
no tool should be forged which can, without prohibitive expense, be 
machined from stock. This generalization practically limits forging 
to lathe and other tools of similar form, made from the solid stock. 
Tools like punches may seem easily forged; but their tendency to burst, 
even when carefully forged, is a sufficient reason for turning down 
from stock rather than forging them. 



CHAPTER VII. 

HARDENING — THE HIGH HEAT TREATMENT PRACTICALLY 

APPLIED. 

Uncertain Results — " Over-Refinement." — As in forging, so in harden- 
ing, very crude apparatus can be utilized, sometimes with satisfactory 
results. For the hardening of an occasional tool only, it might be ad- 
missible to use the protected forge fire already described. But there 
would be no certainty in the results. A tool might, or might not, come 
out right. The only safe course is to use a properly designed furnace. 
If any considerable number of tools are used, a suitable equipment is 
indispensable if it is really desired to make tools which will exhibit the 
powers and advantages of high-speed steel to the fullest extent. The 
derision of over-refined methods, the feeling that tools " good enough " 
can be produced by common, crude methods, has no point. Over- 
refinement is of course possible, and the manufacture of tools can be 
made unnecessarily expensive. But it must not be forgotten that 
" good-enough " in the case of high-speed steel tools means, if it means 
anything, that the tool is properly made and treated, so that it works 
at its best and does not become in the end a very expensive tool by 
failing or by spoiling a lot of work. For all work where endurance and 
accuracy count for anything, that is to say, where tools need to be ac- 
curately sized and to stay so for the maximum time, as well as to work 
during a maximum period, refined appliances and methods represent 
money profitably invested. 

Oil and Coke Furnaces. — The coke or anthracite furnace described 
and illustrated in the preceding chapter, Fig. 47, is well suited to harden- 
ing high-speed tools, as is that shown in Fig. 60, herewith. There are 
also many other suitable coke furnaces in use. When used for harden- 
ing heats, it is desirable that there be some arrangement for suspending 
the tools just above the fire bed, to keep them from contact with the 
fuel. A fire brick hearth or floor can easily be placed just above the 
fire bed, and this will be very convenient in doing some kinds of work. 

The oil furnace is, in general, not suited to the hardening of high- 
speed tools. It is difficult to regulate the temperature or to keep it 
high enough; and ordinarily there is a good deal of oxidation. On 
finished tools this is particularly objectionable. The oxidizing action 
is in some cases partly obviated by the use of a baffle plate or a muffle; 

78 



HARDENING — HIGH HEAT PRACTICALLY APPLIED 



79 



and may indeed be wholly overcome by designing the furnace so that 
the tools are heated within a muffle or a crucible which in turn is raised 




Fig. 60. A coke furnace used in hardening high-speed tools at the royal small-arms factory, 

Enfield Lock, England. 




Fig. 61. Brayshaw twin-chambered hardening furnace, for oil or 
gas fuel. The illustration shows the furnace equipped for 
burning oil. The upper chamber is heated by waste heat from 
the lower, and is used for preheating. 

to a white heat by the rotating flames in the fire chamber. The flames 
must not be directed against the crucible, either in such an oil furnace 



80 



HIGH-SPEED STEEL 



nor in a similarly designed gas furnace, else holes are likely to be melted 
into the pot. An English furnace, Fig. 61, in which the flame is 
directed downward, toward the floor of the fire chamber, is claimed 




Fig. 62. Rockwell oil-burning furnace, complete with tank and blower. A self-contained outfit 
especially adapted to isolated duty. 

to be quite satisfactory; and at least one American furnace, Fig. 62, is 
claimed to have overcome the difficulties and to be well suited to this 
use. 

Gas the Ideal Fuel. — There is some diversity of opinion as to just 
which kind of fuel is best for high-speed steel heating, some maintaining 
that coke is not only ideal, but the only fuel which allows absolute 
control of temperature. On the other hand, the experience of others 
shows that gas furnaces are now made which will accomplish practically 
all that any coke furnace will do. This type is unquestionably the 
most convenient; and while it is true that the first cost of gas seems 
high, when everything is considered, it really is little if any more costly 
than other satisfactory fuels. The objection that in the gas furnace, 
as well as in others mentioned, oxidation of the tool takes place, has 
some foundation. It is true that, as often operated, the heating chamber 
of a gas furnace will contain more or less unconsumed air, and that 
some oxidation takes place as soon as the tools reach a high tempera- 
ture, above a moderate red. Most of this, however, is unnecessary in 



HARDENING — HIGH HEAT PRACTICALLY APPLIED 



81 



a properly designed and intelligently operated furnace, for the supply 
of air and gas will be so regulated that all the air will be consumed. 
The oxidation complained of not infrequently occurs because air currents 
enter the fire chamber through doors carelessly left open. Anyway, 
there is likely to be less of this scaling caused in the furnace than in the 
subsequent exposure in air-cooling, or in carrying to the quenching 
bath. With proper care all except those tools requiring the finest 
finish and the utmost precision can be hardened satisfactorily by using 
gas furnaces for the heating. 

Gas Manufacturing Plant. — This type of furnace can be used even 
where a supply of gas is not available; for fuel gas manufacturing 




Fig. 63. " An apparatus for producing gas from naphtha at a low cost. Desirable where gas is not 
available, or where the cost is excessively high. American Gas Furnace Co. installation. 



plants in size suitable for supplying an equipment of gas furnaces are 
obtainable at a cost and with an economy of production which makes 
them desirable even where artificial gas may be had at the customary 
price. The cost of gas is, generally speaking, in this way reduced at 
least a half. In any event, the cost of the fuel is by no means the most 
important item in the making of high-speed tools; nor indeed is it of 



82 



HIGH-SPEED STEEL 



great consequence in computing the net results. A single expensive 
tool spoiled for want of suitable facilities for hardening it, will pay for 
enough gas to heat a great many other tools. And with inadequate 
equipment many a tool is spoiled, or imperfectly hardened so that it 
falls below its maximum efficiency. Producer gas, it should be stated, 
has not been found well adapted to the production of such high tem- 
peratures as those required in hardening high-speed tools. Oil or coal 
gas is recommended. 

Gas Furnace Design. — Excellent gas furnaces are obtainable at mod- 
erate cost, and it is not intended to discuss here their proper design 

further than to point out a few 
important considerations. A fur- 
nace should be of such form that 
the heating chamber can be, if re- 
quired, entirely enclosed, to pre- 
vent radiation and fluctuation in 
temperature by entering air cur- 
rents. The gas and air should be 
supplied to the fire chamber al- 
ready mixed in proper proportion 
for complete combustion, and so 
directed that the heat falling upon 
the tools is for the most part that 
radiated from the fire-brick walls 
of the chamber or oven. It is de- 
sirable therefore that the flame be 
given a reverberatory movement 
by suitably curved walls or muffle 
plates in the heating chamber, or a 
rotative motion by a tangential 
arrangement of the burners or 
nozzles, so that it will be directed 
past rather than toward the center, 
where it would impinge directly 
upon the tool. The air supply must 
be at a pressure of between one- 
half and two pounds per square 
inch, the air blast inducting the gas. Both air and gas supply must 
be under perfect control. These considerations hold in the case 
of forging and oil-tempering furnaces as well as with those used for 
hardening. 

Electric and Special Furnaces. — More convenient than any other type 
of furnace, and more easily regulated, is the electrically heated; and this 
is coming into considerable use, especially for small work, testing, 




Fig. 64. An excellent type of gas-fired oven fur- 
nace. The flame impinges upon the under side 
of the floor upon which the tools rest. 



HARDENING — HIGH HEAT PRACTICALLY APPLIED 



83 



and the like. Ordinarily the cost of electrical energy, in the operation 
of a large hardening plant, runs rather high. 

For special forms of tools, specially adapted furnaces are desirable. For 
long and slender tools, like taps, drill, reamers, and the like, which are 




Fig. 65. An electrically-heated furnace for hardening small and medium-sized pieces. 




American Mnclnniai' 



Fig. -66. A vertical gas furnace for heating slender tools suspended by their shanks. 
Courtesy of American Gas Furnace Co. 

best hardened suspended from the shank, a cylindrical or rectangular 
vertical furnace is much better than an oven furnace. A modification 
of this form is suitable also for hardening in an empty crucible, as is 



84 HIGH-SPEED STEEL 

sometimes done. It resembles, in its general features, the oil crucible 
furnace already described and is identical with that shown at Fig. 83 
in the chapter dealing with the barium process. Other special forms 
also can be used to advantage where enough work is done to warrant 
their installation. Such is a special die-hardening furnace, which is 
designed to harden only the face of a large die. Oil-tempering and other 




Fig. 67. Stewart cylindrical (gas-fired) crucible furnace, Chicago Flexible Shaft Co. 

furnaces for relieving hardness or strains also are essential to a w T ell 
equipped hardening plant. These will be described in another place. 

The type of furnace to be used will, as may have been inferred, de- 
pend a good deal upon the kind of tool to be hardened, so that it is 
desirable to equip a hardening room with two or three different forms 
to meet the varied requirements. There will also be other appliances 
such as those for quenching, for example. 

Minimum Hardening Equipment. — The minimum equipment to be 
considered will include a combined forging and hardening furnace, 
of any of the kinds already described; and an oil-quenching bath, or a 
stream of air under slight pressure. The apparatus for air-cooling may 
be of the crudest form — nothing more than a pipe of any desired size 
(not too small, say not under f inch), leading from the' air supply and 
provided with a suitable cut-off, or pressure-reducing valve, if compressed 
air is used. Occasionally tools can be hardened with no cooling appara- 
tus whatever, merely being laid in a cool place, preferably where there 
is a current of moving air. This however, is taking long chances on 
tools, for no certain results can be expected under such crude conditions. 



HARDENING — HIGH HEAT PRACTICALLY APPLIED 



85 



A Moderately Complete Outfit. — A fairly complete outfit consists of 
a forge, an oven, hardening furnace, an oil hardening bath or air-cooling 
table, and an oil-tempering furnace. Both the latter are described in 
the paragraphs indicating their use. A well equipped shop for forging 
and treating high-speed steel tools, however, would contain the follow- 



(a) A forge of suitable size for ordinary work. Its use has been 
already indicated. 

(b) A medium (or large, according to the work to be done) oven fur- 
nace for the hardening heats. The small oven furnace or forge would 




Stewart combination gas furnace, with lead bath. 



be used occasionally, no doubt, for small pieces. This furnace could be 
used also for what annealing would be necessary in most hardening 
plants. It would, along with the forge, serve for pre-heating in con- 
nection with the barium bath and crucible furnace, as well as with the 
customary methods of hardening. 

(c) A cylindrical or rectangular vertical furnace of the kind already 
described, for heating long, slender tools which are best suspended 
from one end while being heated. If necessary, for the sake of economy, 



86 HIGH-SPEED STEEL 

this furnace could be easily adapted so as to be suitable, when pro- 
vided with a crucible for that purpose, for hardening in barium chloride, 
or for hardening in a crucible without a bath. 

(d) A lead bath is very useful where there is a wide range of work, but 
is not essential in high-speed tool hardening, especially if a barium 
furnace or a crucible furnace using no bath is adopted. A convenient 
and economical arrangement is a lead bath on the same base with a 
forge and oven furnace, as shown at Fig. 68. This economizes space 
and is very convenient. 

(e) A cylindrical crucible furnace used without a bath. This is less 
convenient than an oven furnace, but is used in some plants because 
it practically prevents oxidation of fine tools while being heated. It 
does not, however, prevent oxidation, to some extent, when the tool is 
exposed to the air before or during cooling; and for that reason, 
among others, it is less desirable than the barium bath furnace. The 
lead bath, barium bath, and empty crucible furnace all can be so made 
as to utilize the cylindrical furnace body by interchangeable crucibles. 
It is of course more convenient to have a furnace of each kind likely 
to be much used in doing the sort of work in hand. In that case, this 
crucible furnace will likely be omitted, unless it is the intention to heat 
tools by this method as a regular practice. 

(/) An oil tempering furnace for " drawing " the temper of such tools 
as require this to be done after hardening. This is described in a later 
chapter. 

(g) A quenching bath or air cooling device. A very simple affair for 
cooling with air has been already referred to, which is quite good enough 
for rough tools of the simpler sort. For careful work a hardening table 
is desirable, and one suitable for this purpose is described in connection 
with the methods of cooling, as likewise is an oil quenching bath. 

Need for a Temperature Gage. — A pyrometer for gaging the tempera- 
ture and checking against the operator's judgment frequently, is es- 
sential to continuous good results. The novice, especially in the manip- 
ulation of the new steels, needs the guidance of such an instrument; 
and the experienced operator himself cannot afford to get along without 
it, especially when working with the barium or other bath process. 
For the latter, a pyrometer of the thermopile or the resistance type is 
generally used; while with the direct heating processes either of these, 
or a radiation pyrometer of the Fery type, can be used. It is well to 
have the fire ends (where this type of pyrometer is used) interchange- 
able on the different furnaces, or with a separate set for each, any one 
of which may be switched into the circuit with the indicator or recorder, 
whichever may be preferred. 

Pyrometers which will give uninterrupted good service under the 
intense temperatures to which they are subjected in this kind of work, 



HARDENING — HIGH HEAT PRACTICALLY APPLIED 87 

are not easily obtainable. The fire ends break after being used but a 
few times; enclosing porcelain tubes crack and crumble; or the thermo- 
couples deteriorate and cease to work properly. In any of these cases 
the indicator or recorder of course does not register correctly, and there- 
fore is of small use, if indeed it does not mislead. When the fire end 
is suspected, it is well to check it with another pyrometer of known ac- 
curacy, or with clay temperature determining cones, sometimes called 
sentinel pyrometers. These latter are very convenient also in the 
absence of a pyrometer, to determine high temperatures. They are 
cheap, accurate and are obtainable in large variety. Each cone is 
numbered for identification, and melts down or fuses when the pre- 
determined temperature has been reached which the particular cone 
was intended to indicate. The cones obviously are not available for 
determining the temperature of a molten substance, as in the case of 
the barium or lead bath. 

Supplemental Equipment. — If any forging is done in the hardening 
room, even though not regularly, there will be also an anvil and the tools 
usually accompanying the same. The anvil illustrated in the previous 
chapter, in connection with the forging of a Taylor standard tool, is 
very convenient. 

There should be provided also a suitable variety of tongs and other 
appliances for handling the tools, some of course of the conventional 
forms used for the purpose, and others especially adapted to the han- 
dling of tools requiring to be heated all over or which for other reasons 
cannot well be handled by ordinary tongs. The jaws of ordinary 
tongs, covering as they do a more or less considerable portion of the sur- 
face of the tool in hand, affect the temperature of the parts so covered 
and likewise prevent their coming into free contact with the oil or air 
in cooling. The excellence of the tool is thus impaired, often to a con- 
siderable extent. Many failures to secure results with high-speed steel, 
to say nothing of ordinary tools, are unquestionably due to so apparently 
small a thing as this. 

In some instances tongs with in-curving ends, properly formed to grasp 
the tools, are useful; in others the jaws may be studded with projecting 
hobs or prongs so that but a small amount of relatively cold metal 
touches the tool. Various desirable forms will doubtless suggest them- 
selves as the occasion arises for their use. 

Arrangement of Hardening Room. — The arrangement of the various 
furnaces and baths will depend much upon the number to be installed, 
and the limitations of the hardening plant — among other things, 
whether or not carbon steel tools, or even other objects, are to be hard- 
ened also. Assuming that a hardening plant for high-speed tools only 
is contemplated, and is equipped with the appliances enumerated above, 
the arrangement would be somewhat like that shown in Fig. 69. At 



88 



HIGH-SPEED STEEL 



the extreme end would be the forge, and opposite it the anvil; next 
the small hardening furnace, if there be one, and the medium or large 
oven furnace; and beyond them the cylindrical and the barium furnace. 
Opposite these is the best place for the air table and oil bath, or either, 
if but one is to be used. On the same side with the quenching appli- 
ances and ranged at one side of them, are the lead bath, if there be one, 
and the oil tempering furnace. It is seen that this arrangement econo- 
mizes space and practically centers the furnaces about the air table 
and quenching bath. The circular arrangement is avoided, though it is 
rather more convenient, because the space in which the operator works 
will doubtless be found quite hot enough without having focused upon 



V 





Fig. 



Layout of hardening room of capacity sufficient for hardening all the tools used in a large 
manufacturing plant. 



him the radiation of all the furnaces which happen to be in use at one 
time. If coke furnaces are used, the arrangement would be different only 
to the extent that these replace the gas furnaces here contemplated. There 
would perhaps be fewer of them, but each would occupy more space. 

Provision for Ventilating. — Each furnace and bath should be provided 
with a hood, preferably telescoping so as to permit lowering or raising 
as occasion may require, to carry away fumes, smoke, and excess heat. 
It is desirable that the hoods be connected to a common vent which 
is exhausted by a fan. This will not only keep the room free of fumes, 
but will add greatly to the comfort of the operator by creating a cooling 
draft. The fumes from the lead bath at the high temperatures to which 
it is necessarily raised, and from the barium bath also under certain 
conditions, are very irritating and must not be allowed in the room. 
It is well also to jacket the furnaces. 



HARDENING — HIGH HEAT PRACTICALLY APPLIED 



89 




90 



HIGH-SPEED STEEL 




Fig. 71. 



" Each furnace and bath should be provided with a hood, properly connected to an exhaust.' 
Individual hoods, one for each furnace, are to be preferred. 




Fig. 72. Hardening room, Standard Tool Company, Cleveland. The furnaces are surrounded by a 
continuous sheet-metal jacket to prevent the distribution of heat into the room. Light is made even 
by the baffle shutters. 



HARDENING — HIGH HEAT PRACTICALLY APPLIED 91 

Heating Simple Tools. — Heating high-speed tools for hardening is 
a very different thing from heating them for forging, not only with 
respect to the temperature, but to the variation in method also. The 
way in which a tool is heated and quenched, in hardening, depends 
very much upon its form and the use to which it is to be put. 

Lathe, planer, slotting, boring and the like tools can for the most 
part be readily ground to shape after hardening, and are on that account 
the simplest to treat. The heating may be done in any of the furnaces 
already designated as suitable for the purpose. It has been done 
successfully also in an ordinary smith's forge, though as already pointed 
out this method is not reliable and is undoubtedly responsible for many 
disappointments and failures. If no better means of heating are at hand, 
the forge fire should be covered with a hood, as already described in 
the chapter on forging, and the bricks well heated before any tools are 
placed in the fire. 

Gradual Heating Required. — When using a fire of this kind, or a coke 
furnace alone, it is well to place a number of tools toward the edges of 
the fire or upon the ample foreplate provided for that purpose in the 
case of the coke furnace, bringing each in turn nearer to the hottest 
part of the fire. This allows of slowly bringing the temperature up to 
a bright red, about 1,000 degrees C. (1,800 F.). When this heat has been 
reached the tool may then be rapidly brought to a dazzling white, 
anywhere above 1,200 degrees C. (2,200 F.), so the surface begins to flux 
and the corners and edges show signs of melting down. A few steels 
will harden properly somewhat below this temperature, and it is well 
to note and follow the direc- 
tions of the makers on this point. 
There need be no fear of over- 
heating, for as a rule no good 
high-speed steel is injured by 
any heat to which it can be 
subjected in any fire such as has 
been here described. 

Time and Extent of Heating. 
— The time required for bring- 
ing a tool from the red to the 
white heat will of course vary 
with the size of the tool and the 
intensity of the heat. Under 

gOOd Conditions it Should not " ba( : k than neC e S sary. The line AB indicates ap- 

need to take more than two ^5?^*^ to which ^ tool '' hould be 
minutes for a one-inch tool. 

It is important that the heat soak into the interior of the nose or working 
part so that it is uniformly hot throughout; and that while the whole 





92 HIGH-SPEED STEEL 

of the nose is so heated, the heat shall not soak up into the neck of the 
tool. The white heat should not pass beyond the line AB, shown in 
Fig. 73. It is to be noted also that some makers of these steels recom- 
mend that the heating be gradual from the cold to the intensest white. 
This, however, does not seem to be really necessary, and it is usually 
more convenient to heat, in the way indicated above slowly to a red 
and rapidly afterward to a dazzling white. 

Using the Gas Furnace . — If a gas furnace is used to give the harden- 
ing heat, rather more care must be taken to keep the white heat in the 
nose of the tool. It is on that account desirable that tools of this kind 
be suspended through an opening in the top of the furnace, so the ex- 
tent of the heating can be controlled as closely as necessary by the 
distance to which they protrude into the heating chamber. It is de- 
sirable that the first or slow heat be given in a pre-heating furnace, the 
temperature of which is kept at or near a red heat, say about 700 or 
800 degrees C. (1,300 to 1,500 F.). The tools are transferred to the high- 
heat furnace as rapidly as they can be handled conveniently. This serves 
the double purpose of preventing, in the case of large tools, the sudden 
lowering of the high temperature in the hardening furnace and the 
consequent need for regulating it again, and the blistering effect upon 
the surface of tools thrust cold into a furnace at white heat. Not only 
is the surface blistered under these circumstances, but the outside of 
the tool heats so rapidly that corners will be melted down and the tool 
will have the appearance of being ready for cooling when as a matter of 
fact the interior probably has not nearly reached the required tempera- 
ture. A tool hardened in this way very naturally would be defective. 

Grinding to Shape before Hardening. — In order to avoid excessive 
grinding of the hardened tool, it should be brought pretty closely to 
the required shape on a dry emery wheel after cooling down from the 
forging heat and before being subjected to the hardening heat. Some 
allowance must of course be made for the grinding subsequent to the 
hardening, to remove the burnt skin and restore the cutting edge. 

Precautions Necessary.— All tools with projecting edges, grained surfaces, 
sharp angles, or many clearances, are peculiarly susceptible to cracking 
during and after hardening unless this has been carefully and properly done. 
It is evident, therefore, that all possible precautions should be taken, by 
the use not only of care and intelligence in the treatment, but of adequate 
and approved special appliances whenever these have been shown by 
experience to help bring the best results. The need for certain special 
hardening furnaces indicated in a previous paragraph is made very 
evident when tools of the classes just mentioned are to be hardened. 

Suspending Slender Tools. — Such tools as long taps, reamers, drills, 
and the like, especially when slender, are very liable to warping and 
bending, unless heated (and cooled also) in a vertical position. They 



HARDENING — HIGH HEAT PRACTICALLY APPLIED 93 

should therefore be suspended by their shanks during the heating. A 
vertical furnace such as has been already described, and illustrated in 
Fig. 66, is desirable for this purpose, though a coke furnace could have 
its top suitably arranged to allow of the same thing. The shanks of 
the tools project through holes in the cover of the furnace and they are 
held in place by tongs or holders provided for that purpose. The pre- 
heating can be carried on in any convenient way. 

Temperature Limits. — The temperature is not carried as high as in 
the case of tools which can be ground after hardening, and must always 
be short of the point where the cutting edges begin to melt. The limit 
of temperature is about 1,250 degrees C. (2,300 F.) except for heavy rough- 
ing cutters, when it is 50 to 100 Centigrade degrees higher, and may 
range downward to a hundred degrees below that point, or from a mel- 
low white or light straw to a bright lemon or very light orange color. 
Where the tools are of such a kind that the cutting edge can conveniently 
be re-ground after hardening, the heat may be carried up to that gener- 
ally given to forged tools, or a little above 1,300 degrees C. (2,400 F.). 
Tools for most lands of work are the better for this, if they will allow 
of the higher heat. The tools must not be allowed to touch the fuel 
nor be exposed to a flame after reaching a yellow heat, lest the cutting 
edges be injured. It must be remembered that, as in the hardening 
of all high-speed tools (except as pointed out in the chapter dealing 
with the barium process), the heating must proceed evenly throughout 
the tool or throughout that part which is to be hardened. Otherwise, 
strains are sure to be set up during the cooling, which are not relieved 
by the ordinary methods of tempering even, and which inevitably 
affect the endurance of the tool. All tools of intricate shape are pecu- 
liarly susceptible to cracking from such strains, the defects frequently 
appearing long after the tools have been set at work, if not immediately 
after the cooling. 

Watch the Pyrometer Indicator. — Success in hardening these tools 
depends very largely in getting just the right temperature in the heating. 
It is very necessary, therefore, to watch carefully the progress of the 
heating when the color begins to verge on a light yellow, so that the 
cutting edges shall not be damaged and a crust formed which would 
afterward need grinding off and thus affect the size of the tool. It is 
well to consult the pyrometer frequently at this point, for the varying 
conditions of light on different days and even in different parts of the 
same day are quite enough to affect the judgment of the operator. 

Milling Cutters and Like Tools. — Milling cutters and similar formed 
tools are heated in practically the same way as are tools of the kind 
just considered, except that the cylindrical furnace is not used. It is 
no better than the oven furnace for these tools, if as good. The cutting 
teeth or edges must however be kept from contact with fuel or furnace 



94 HIGH-SPEED STEEL 

walls and floors, and it is well therefore to set such tools on end upon 
pieces of fire brick of appropriate size, or to suspend them from above 
by a suitable arrangement. 

Unless this precaution is taken the keenness of the edges is almost 
sure to be impaired, if indeed the hardening also be not affected. For 
the same reasons, more especially because the proper hardening is sure 
to be affected, in handling tools of this sort, tongs or other appliances 
must be used which will not touch the cutting edges. 

If such tools are of necessity heated in a forge fire, they should be, 
like drills and reamers, frequently turned; and it is well to do this 
however they may be heated. The cutting edges must not be allowed, 
when at a yellow heat or above, to rub against the fuel; and it is better 
that they do not even come into contact with it. This is one of the 
reasons why a forge fire is not well suited to the hardening of fine tools. 
Another reason is the oxidation which inevitably takes place to a greater 
or less extent under such crude conditions. 

Oxidation and its Prevention. — To protect such tools, heated under 
these conditions, from scaling and impairment of edges, a file-maker's 
paste, sometimes called a hardening paste, has been used by some. 
This however, while possibly serving the purpose desired to a consider- 
able extent, leaves the surface of the tool unclean, so that the hardening 
is not infrequently affected. 

The oxidation trouble is often very annoying, when it is not prevented, 
necessitating the re-grinding of tools after hardening and consequently also 
necessitating making them in the first place enough larger than the 
finished size to provide for this contingency. Except in the forge fire, 
oxidation need not occur to any considerable extent in any properly 
designed and intelligently operated furnace. Ordinarily most of the 
oxidation takes place after removal from the furnace and while the tool is 
exposed to the air. It is desirable therefore that tools be not carried, 
exposed to the air, any considerable distance for the cooling. This is 
imperative in the case of fine tools and those with sharp edges, unless 
they have been heated in the barium chloride bath. 

Lead Bath and Pack-Hardening. — It is to prevent oxidation entirely that 
the lead bath, the empty crucible muffle furnace, and like means, have been 
resorted to. These will be further considered in connection with the 
barium process, in a separate chapter. The " pack-hardening " of fine 
tools serves its purpose quite effectively, but is now little practiced be- 
cause the same results can be obtained by less troublesome means. Where 
adequate facilities for getting the same results in a quicker and more cer- 
tain way are wanting the method still serves a purpose. The usual 
practice is to enclose the cutters, if small, in a piece of wrought-iron 
pipe, packed closely with charcoal, fine coke, or other customary pack- 
ing, with the ends of the pipe sealed with clay. If much of this sort 



HARDENING — HIGH HEAT PRACTICALLY APPLIED 



95 



of work is to be dojie there should be a suitable pot, preferably of wrought 
iron. Cast iron will do, but it must be expected that the bottom will 
drop out occasionally, so intense is the heat required. Tools placed in 
the packing case should not touch one another, and, where this can be 
done conveniently, should be suspended by a common support before 
packing, to facilitate their subsequent removal and quenching (Fig. 74). 
The pot and contents, after sealing up, are placed in the white-hot fur- 
nace until the whole is at the uniform high heat necessary for hardening 
the particular kind of tools in hand. No rule can be laid down for the 
length of time required, since that will depend entirely upon the size of 
the tools and pot. The operator must be guided by experience — and 
the pyrometer. Some indications as to the condition of the tools may 




Charcoal or Coke 



The Engineering JUagasine 



Fig. 74. Pot for "pack hardening" tools, with method of suspending cutters for 
convenient handling and avoidance of contact in quenching. 



be obtained by the old expedient of withdrawing from time to time 
wires previously inserted in the pot for that purpose. The contents 
having reached the necessary temperature, the pot is withdrawn, and 
its contents removed and quenched as rapidly as possible. 

Causes of Scaling. — It may be of interest to mention the causes of 
scaling or oxidation. The explanation is very simple. At high heats 
iron and oxygen (which latter constitutes about a fifth of the atmosphere) 
have a keen chemical affinity for each other, and the oxygen of the air 
attacks the hot iron (or steel) with great avidity. The resultant of their 
chemical combination is a scale constituted of iron oxide, which is the 
same as common red iron rust except that the latter contains some 
water while the former does not. Scaling takes place also when steel or 
iron is left in contact with fuel through which air is passing or with 
which air is mixed. Hence the need for the cautions previously given 
with reference to such contact. 

Special Methods. — The need for exceeding care and the use of suitable 
appliances in the hardening of high speed steel tools, in order to insure 
proper and uniform hardening and to avoid deformation of their shape, 



96 HIGH-SPEED STEEL 

has been already referred to several times. Nevertheless its importance 
warrants still further mention of the matter, especially in connection 
with the use of gas or other furnaces with floors or hearths. Tools of 
compact shape can, when so heated, be placed directly upon the floor 
of the heating chamber, or preferably upon pieces of fire brick; and are 
removed in the ordinary manner, the tongs of course being suited to the 
purpose. Long and slender tools, and others which are likely to be 
deformed, may be laid upon bricks or bars which have been carefully 
leveled, and are removed by the aid of pronged bars or other suitable 
implements. To expedite the heating of many small tools, say like 
inserted cutter blades, they are laid upon parallel bars which in turn 
rest upon the floor of the furnace. A flat bar or suitably pronged rod 
can be used for placing or removing a whole row of them at once. In 
all these cases the implement used for handling the pieces is to be well 
heated up before lifting them out, for reasons already assigned. 

Punches, Shear Blades, etc. — For hardening punches, punch dies, shear 
blades, forming dies, and a variety of other tools more or less like them 
in use, the heat is not brought as high, generally speaking, as for those 
classes of tools already considered. These tools preferably are ground 
closely to shape before being hardened. The temperature is in all cases 
kept below a clear white heat — say at a lemon color or near 1150 degrees 
C. (2100 F.). From this it may range downward, according to the brand 
of steel used and the size of the tool, to a very bright red, about 950 
degrees C. (1750 F.). Small shear blades hardened at the higher tempera- 
ture named give excellent service without being tempered. Chisels and 
other tools subjected to repeated shocks are taken at the lower tem- 
perature mentioned. 

Summary of Hardening Temperatures. — For convenience of reference 
the temperatures required for hardening the various kinds of high- 
speed tools are here summarized. Turning, planing, shaping, slotting, 
boring, and the like tools for roughing and medium cuts: a full to a 
dazzling white, as high a temperature as can be given without actually 
melting the tools. Melting does not occur, in most high-speed steels, below 
1400 degrees C. (2550 F.). 

Milling cutters and similar tools for heavy roughing: a good white, 
1300 or 1350 degrees C. (2375 to 2450 F.). 

Milling cutters for moderately light and finishing cuts, forming cutters, 
screw machine tools, tools for fine finishing, and those which are to hold 
keen edges where the strain is not great, tools for cutting brass, and 
nearly all woodworking tools: a mellow white or light straw, or a little 
deeper, say from 1250 to 1200, or even 1150 degrees C.(2300, 2200, 2100 F.). 

Twist and flat drills, reamers, threading dies and taps, and other 
tools subject to severe torsional strains: slightly lower than that given 
above, or say a little below 1200 degrees C. and down to about 1175 (2200 



HARDENING — HIGH HEAT PRACTICALLY APPLIED 97 

to 2150 F.) or slightly below. This would give a light lemon color, verg- 
ing into straw. It will not greatly matter if these tools be heated quite 
as high as those in the class above, though in general rather better results 
will follow if this difference be observed. 

Shear blades, punches and punch dies, stamping and forming dies, 
pneumatic tools and others subjected to repeated jars or blows: 950 to 
1150 degrees C. (1750 to 1900 F.) or from a bright cherry red to a light 
orange or lemon, according to the shape and use of the tool. Light 
punches and snap dies would be given the lower heats, as also would 
tools like file-cutting chisels. 

Permissible Temperature Variations. — It should be remembered in 
connection with the above summary that the hardening temperatures of 
high-speed steels vary more or less according to the composition, and 
that it is well to observe closely the instructions of the makers relative 
to this point, or better still to make careful determinations when any 
given steel is to be used, and thereafter to observe the limits found to be 
most satisfactory. In the nature of the case the above determinations 
are only general; but it is asserted with confidence that but little vari- 
ation will be found desirable in the case of any high-speed steel of the 
now accepted standard composition — if it is not premature to speak 
of a standard composition. 

Quenching Agents — Water. — For cooling high-speed tools either air 
or oil is used to good advantage. Cold water is, in general, to be avoided 
in cooling high-speed steels, whether of the so-called " new " varieties 
or not. Quenching in cold salt water is of course possible, and has in 
some cases been recommended by makers. Nevertheless hot high-speed 
steel and cold water are not a safe combination. A tool so cooled may 
not crack; and indeed may perhaps be repeatedly quenched in water — 
and again it may crack the first time, or strains may be set up which 
will cause cracks later. The uncertainty of the method, if nothing else, 
makes it a good thing to avoid except possibly in those cases where 
extreme hardness is requisite and the danger of cracking can be over- 
looked. Hot water, speaking in a general way, is less likely than cold 
to cause cracking, and has been used successfully for obtaining extreme 
hardness. It is best kept at a temperature rather above 70 degrees C. 
(160 F.). The novice will do well to let water alone as a quenching 
agent. 

Air Cooling. — In the early days of high-speed steel air was recom- 
mended by most makers, to the exclusion of oil. It is coming to be 
pretty generally agreed now that if oil does not give better results, as 
some maintain, it at least does give quite as good as air, and that it has 
some advantages not possessed by the latter. Inasmuch as most high- 
speed steels harden by mere exposure to the air, little apparatus is abso- 
lutely required, as has been already noted. Some rather good results 



98 



HIGH-SPEED STEEL 



have been obtained in this simple way. The hardness of these steels, 
however, depends a good deal upon the rapidity and the method of cool- 
ing, on which account mere exposure to the air does not bring out the 
qualities of the tools to anything like their highest degree. For many 
tools, therefore, this method is out of the question. To obtain uniformly 
good results the air should be cool and in motion. Preferably it is 
supplied in a continuous and rapid stream, large in volume rather than 
high in pressure. Compressed air is better than that from a blower. 
The pressure must, however, be reduced to two or three pounds only at 
the nozzle. 

Apparatus for Air Quenching. — For hardening an occasional tool, as 
has been already indicated, nothing further is required than a supply 
of air coming from a suitable nozzle of ample size. The tool is held in the 
blast and turned continuously until cold enough to handle, when it is laid 

aside in a dry place. Where many 
tools are to be hardened, even if 
only of the simplest kind, it is very 
desirable that there be a cooling 
table where the tools can be me- 
chanically held and turned while 
the air blast plays upon them. 
Such an arrangement is almost in- 
dispensable in the case of rotary 
cutters. A cooling table of simple 

Fig. 75. Table for air-hardening revolving cutters, as . - . . . 

used at the Royal Small-Arms Factory, Enfield design, Used in the British Koyal 

oc ' ngan • Small-Arms Factory at Enfield 

Lock, is shown in Fig. 75. It consists essentially of an iron-top table 
provided with a rotating plate and spindle between two movable nozzles 
from which the air blast issues 
The spindle and plate can be pro- 
vided with a clamp for holding lathe 
and similar tools also. In cooling 
milling cutters and the like, the 
nozzles are turned to one side of 
the center of the cutter so that the 
air will impinge upon the pro j ecting 
teeth in such a way that they will 
act as vanes, and the cutter be 
therefore rapidly rotated by the 
air current. All cutting edges are 
in this way cooled with absolute 
uniformity. An air box, resem- 
bling that illustrated at Fig. 76, is desirable for cooling lathe and similar 
tools. 





L Air Plpo 



Fig. 76. Air box for air cooling of high-speed tools. 
Convenient for hardening lathe tools and those 
of similar shape. 



HARDENING — HIGH HEAT PRACTICALLY APPLIED 



99 



6 
6 
A 
6 

Air bubbles 

6 




DeUdubU "Ira act toskei 

4 4 4 



4 4 «, 

Wlr* oet to catch tool! dropped 
Net U itre&gtbeoed bj croto b*i» 



6 d / 

N«t frame of Angle Iron 

6 6 

4 « 

4 • ^ 

Ug for support^ net 

4 
t 

6 



O if o 

\ Peif« 



Mod 

mppl; pipe 
tod Ittcnli 



The convenience and simplicity of this method of hardening certainly 
recommend it. There are, however, certain disadvantages. The cost 
of air, for one thing, is considerable, and not comparable with that of 
maintaining an oil bath. The first cost of the latter is also the last cost 
except for the negligible item of renewal. In the air blast, furthermore, 
in spite of the rapidity of the cooling and the exercise of the greatest care, 
there will frequently be more or 
less oxidation; and this is not per- 
missible, in fine tools at any rate, 
affecting their precision as it does. 
Scaling is unimportant in the case 
of rough tools, since they are well 
ground anyway after hardening. 
Tools cooled in air are, in general, 
rather slightly softer than those 
cooled in oil. 

Apparatus for Oil Quenching. — 
For oil hardening the apparatus 
may be almost as simple as for air 
hardening. In small shops where 
but few tools are treated, nothing 
more is required than a medium 
sized tank full of oil. The shop 
doing a good deal of hardening, 
however, needs a bath of ample 
size equipped with some device 
for cooling and circulating the oil. 
An excellent form of such an ap- 
paratus is shown in Fig. 77. It is 
seen to consist of a sheet metal 
tank of suitable size, having a sup- 
ply pipe and laterals at the bottom 
through which air under slight 
pressure is introduced. The pipes 
have small holes in their upper sides from which the air bubbles up 
through the oil, at the same time cooling and circulating it. A net for 
catching tools accidentally dropped is desirable, as also is a net basket 
at one side, into which small tools may be thrown from time to time, for 
quenching, without further attention. 

Kind of Oil to Use. — Various oils have been recommended for quench- 
ing high-speed steel, including linseed, cotton seed, rape, fish, whale, 
lard, tallow, paraffme, and even kerosene. It does not matter particu- 
larly, so far as the effect upon tools is concerned, which is used, as long 
as it is thin and does not become gummy. Some have certain disad- 




Fig. 77. Excellent design for oil-hardening bath. 



100 HIGH-SPEED STEEL 

vantages, though, which it is well to consider. Kerosene oil has given 
better satisfaction than anything else in some hardening plants. It 
does not flash, as might be expected, upon the hot tool coming in con- 
tact with the surface unless the quenching is very awkwardly done. 
If the tool is plunged quickly to a point below the heated portion, 
or entirely in the case of tools heated throughout, there will be no 
flashing. 

Disadvantages of Certain Oils. — Whale and fish oil are excellent agents, 
but have offensive odors. These can easily be suppressed, however, by 
the addition of about three per cent of heavy (tempering) oil. This 
at first floats upon the surface, but usually mixes with the lighter oil in 
time. The hardening is not affected by the heavy oil added, and this 
combination is about as satisfactory as any could be. 

Linseed oil is too gummy for general use. Lard oil becomes more or 
less rancid in time, but is excellent; and cotton seed oil has practically 
no objectionable features. The point is not so much what kind of oil 
is used; but that the supply be ample to absorb the heat rapidly from 
the tool. Where much hardening is done it is of course necessary, as 
already noted, to provide a means for stirring and cooling the oil. 

Cautions as to Quenching. — The quenching itself seems, and indeed is, 
a simple matter. There are, however, some points that should be care- 
fully observed, to get uniformly good results. First, the quenching must 
be done rapidly. Not only is the tool to be plunged into the oil with 
the least possible interval between this and the removal from the fur- 
nace, to avoid oxidation; but the plunging itself should be quickly done. 
Circular cutting tools, like milling cutters, are plunged with the axis 
vertical unless the thickness is considerably less than the diameter. 
In that case they are quenched like thin dies; that is, in an upright 
position. Most other tools can be plunged with the long axis vertical. 
After immersion the tool can of course be turned to any position 
that may be convenient. The vertical plunging obviates to the largest 
possible extent the warping and cracking to which intricate tools, and 
even those which are not intricate, if carelessly quenched, are subject. 
A thin, flat die with relatively large surface, for example, if quenched 
so that one face strikes the oil before the other, even if the intervening 
time be infinitesimal, almost invariably is warped and becomes useless. 

Special Case of Slender Tools. — In the case of drills, reamers, and the 
like, the heating of course has not extended the full length of the fluted 
part (unless, as rarely happens, the whole length is intended to do work), 
and the quenching does not go beyond the heated portion, say not 
beyond where it is still a good red. This can well be laid down as a 
general rule: a tool, except as already indicated, should be plunged to a 
point rather nearer the edge or end than that to which it has been heated, 
and worked up and down slightly while cooling. In this way a distinct 



HARDENING — HIGH HEAT PRACTICALLY APPLIED 101 

line of demarkation between hardened and unhardened portions will be 
avoided, and the snapping of tools at this place prevented. 

Large or Intricate Tools. — If of any considerable size the tool must be 
kept moving in the bath so that all parts immersed will be washed by- 
cool oil, otherwise the oil in contact with the surface becomes so hot that 
hardening does not take place properly. This is especially true of 
tools of intricate shape, with many recesses, or containing small holes. 
In the last named case the tool should be so moved in the bath that oil 
will flow freely into and through the openings. If several tools are 
quenched simultaneously care should be taken that they do not touch 
one another, lest the places touching fail to come into free contact with 
the oil and consequently do not harden properly. 

Essentials of the Hardening Method. — The method of hardening here 
described involves essentially this: The tool is heated to the highest 
temperature it will bear without injury to the cutting edge, and even to 
the melting point if it can be afterwards well ground. It is then quickly 
cooled in an air blast or in an oil bath. This process is simpler than 
that patented by Taylor and White, is much more used, and is quite 
generally conceded to give results equally good with practically all 
standard high-speed steels. 

Essentials of the Taylor-White Process. — The Taylor- White process 
consists in the following steps : 

First, the high-heat treatment. The tool is heated to the highest 
temperature it will bear, as in the general process already described. 
It is then cooled rapidly down to the " breaking down " point, about 
850 degrees C. (1550 F.), and after this cooled more or less slowly, as may 
be convenient. The method recommended by the patentees, for the 
preliminary cooling, is to plunge the tools from the high heat into a 
lead bath maintained at a constant temperature of 625 degrees C. (1150 
F.), and to hold them there until they have had time to reach that tem- 
perature throughout their entire mass. Mr. Taylor says * it is a matter 
of no particular importance whether the^ tool be cooled rapidly or slowly 
below the " breaking down " point; and indicates that it may just as 
well be cooled in the air blast as not, and does quite well if merely laid 
aside to cool in the normal atmosphere. 

Second, the low-heat treatment. The tool is reheated to somewhere 
between 375 and 675, say to approximately 625 degrees C. (1150 F.), pref- 
erably in a lead bath large enough to maintain a uniform temperature. 
The tool is kept at this temperature for about five minutes, and is then 
cooled, whether rapidly or slowly being a matter of indifference. 

Taylor- White and Other Methods. — The only essential difference be- 
tween the Taylor- White and the customary process is seen to be in the 

1 See Appendix B. 



102 HIGH-SPEED STEEL 

second or low-heat treatment, which is omitted in ordinary practice. 
In another place mention is made that high-speed tools do not run at 
their best until a short time after being set at work, after being " warmed 
up," so to speak. The warming up is not figurative, but real. The tool 
soon attains a temperature approximating the minimum above given, 
that is, 375 degrees C, and therefore accomplishes while at work what is 
intended to be accomplished by the low-heat treatment. The " self- 
treatment " thus received by a tool does not normally give so high a 
temperature as that recommended by Mr. Taylor, unless run so rapidly 
that the cutting edge becomes red hot — which is not good practice, 
generally speaking. The cooling naturally occurs when the tool is 
stopped preparatory to taking the next cut. Apparently, therefore, 
the second or low-heat treatment is superfluous. It is maintained, 
nevertheless, that the self-treatment just referred to does not accom- 
plish to the same extent what the low-heat treatment does, the tempera- 
ture to which the tool is raised being rather too low under ordinary 
circumstances. However that may be, the second treatment is all 
but universally dispensed with, and so far as can be seen without dis- 
advantage. 

Special Modifications. — A modification of the Taylor- White high-heat 
part of the treatment is sometimes recommended by the makers of 
particular brands of high-speed steel. The tool, after being brought 
to the requisite high heat, is transferred to a hot bath of some kind, 
whether lead, fusible salts, or the like, where it is cooled to a dull red, 
equivalent to a temperature near 675 degrees C. (1250 F.), or 690 degrees 
C. (1280 F.), according to one successful maker of many tools. It is 
then removed from the bath and allowed to cool naturally, or it may be 
rapidly cooled in an air blast or by quenching in oil. Mr. Gledhill 
recommends a still further modification, cooling to the point mentioned 
above or slightly higher, in the air or in a blast, and then quenching in oil. 
As a matter of fact it would seem that the manner of cooling is relatively 
of small consequence, except that if it be rather rapid in the first stage 
the result will be a somewhat better tool. But the high heat is absolutely 
essential; and the higher the heat, the better the tool — subject, of 
course, to the limitations already pointed out. 

Electrical Hardening. — High-speed tools may be hardened electri- 
cally, though the process has not come into very general use. No definite 
information is at hand as to the excellence of the tools so treated, though 
the results are said to be satisfactory. Two methods have been prac- 
ticed to some extent. 

In the first method, illustrated in Fig. 78, the tool forms the positive 
electrode of an electric circuit in which it is placed by being clamped 
in a suitable clip or holder. The other electrode is constituted of the 
walls of a cast-iron tank containing a strong solution of potassium car- 



HARDENING — HIGH HEAT PRACTICALLY APPLIED 



103 



bonate. There are, of course, the necessary fuses, switches, and, current 
regulators. The current having been turned on, the tool is gently 
lowered, into the solution to the depth to which it is to be hardened, 



FLEXIBLE CABLE 




Fig. 78. Arrangement of apparatus for hardening tools electrically by use of potassium carbonate bath. 

and moved, up and down a little so as to avoid an abrupt transition from 
hardened to unhardened part. The tool on entering the bath completes 




Fig. 79. Arrangement of apparatus for hardening electrically by use of the electric arc. The shaded 
portion in B indicates the location of the carbon point during the heating. The cooling is by air blast 
or oil bath, as in the ordinary method. 

the electric circuit, and an intense heat is set up in the part immersed. 
When this is seen to be sufficiently heated, the current is switched off 
and the tool allowed to cool in the solution as though in an oil bath. 



104 HIGH-SPEED STEEL 

In the second method (Fig. 79) the electric arc is utilized. The tool 
is placed on an insulating block and attached to the positive electrode. 
The other electrode is a stick of carbon clamped in a safety holder. 
The current being on, at a low voltage, the carbon is touched to the part 
of the tool to be hardened, and moved about as desired until the required 
heat has been attained, the voltage being gradually increased through 
a suitable rheostat. The tool is then cooled in the customary manner. 
This method evidently is suited only to local hardening, and not to the 
general run of tools. 



CHAPTER VIII. 

HARDENING — THE BARIUM CHLORIDE PROCESS. 1 

Preventing Oxidation.— The scaling or oxidizing of fine tools has been 
already referred to as troublesome in certain cases; and ways have been 




Fig. 80. A cylindrical gas furnace fitted for use with the barium chloride process. 
Crucible filled with melted salts and ready for use. 

1 While the hardening of high-speed steel by the barium process was originated in 
Europe, it seems not to have been made commercially practicable until it was taken 
up in this country by the agents of the Firth-Sterling Steel Company (Wheelock, Love- 
joy & Co. in New York and Boston, and E. S. Jackman & Co. in Chicago) and per- 

105 



106 



HIGH-SPEED STEEL 



pointed out by which this annoyance, and the attendant expense of re- 
finishing, could be minimized with such appliances as might reasonably 
be expected to form part of a moderately well equipped hardening plant. 
Even before the days of high-speed steel it was felt that there should 
be some means of entirely obviating the nuisance; and many methods 
have been devised to that end, a number of them entirely successful 
except for one thing. The coke furnace, the well-regulated gas furnace, 
and possibly other ordinary furnaces give, as already remarked, very 
satisfactory results except as to tools requiring a fine finish; and the 




Fig. 8L Good example of intricate tools readily hardened by the barium process. 

electric furnace, and the crucible furnace in which the tool is heated in 
a white-hot crucible, which in turn is heated preferably by gas or oil, 
entirely prevent oxidation during the heating process if proper pre- 
cautions are taken. So also do the lead bath and the pack-hardening 
method. But none of these methods takes cognizance of the fact that 
even though a tool may come out of the furnace absolutely undamaged 
by oxidation, the moment it is removed and comes into contact with 
the air it is immediately attacked and oxidation takes place to a greater 
or less extent according as the exposure prior to cooling to the normal 
temperature is long or short. To overcome the difficulty entirely it 
would appear necessary to quench tools of the kind indicated without 

fected for the treatment of their Blue Chip steel. It is stated by the makers of a few 
high-speed steels that their steels will not harden properly by this process. This is 
anomalous, if true. However that may be, the process, developed. only yesterday, as 
it were, and as yet doubtless capable of great improvement, has been already adopted 
or is now being adopted by all the leading makers of fine high speed steel tools. 



HARDENING— THE BARIUM .CHLORIDE PROCESS 107 

bringing them into the air at all. This it has been impossible to do 
with the appliances in general use, until the discovery and practical 
development of the barium chloride process. 

Advantages of the Barium Bath. — There are, of course, other reasons 
for the use of a bath in hardening fine tools. One of the most important 
is the need for absolute control of the temperature to within a very few 
degrees, and absolute uniformity in heating through every projection 
and into every recess, in the case of intricate tools, especially when small. 
While ordinary furnaces, such as have been recommended, are in general 
very reliable, and their temperatures under sufficiently close control 
for most purposes, there are nevertheless some fluctuations occasioned 
by variations in pressure of the gas supply or of the air pressure, and 
in the size of the door and other openings during the heating. These 
fluctuations are insufficient in the case of large tools, generally speaking, 
to be harmful, because of the comparatively long time required to bring 
such tools to the required heat, even when introduced into the heating 
chamber after being preheated. The small tool, because of its little 
mass and consequently the short time required for heating, is liable to 
be brought to a temperature sufficiently different from the one intended, 
to affect its quality to a considerable extent. Furthermore, in spite of 
frequent turnings and other precautions, some parts of tools complicated 
in shape will heat faster than others by their closer proximity to the 
incandescent walls of the heating chamber, or because of the direction 
of the currents which circulate within it. This is of course of less conse- 
quence in large tools than in small or fine ones with delicate projections 
or keen edges. 

Difficulties in Use of Lead Bath. — Another difficulty, the remedy for 
which, in the case of certain classes Of tools, has been already pointed 
out, is that of warping while being hardened. Slender tools (like drills, 
reamers, and those of similar shape) of a size sufficiently large to admit 
of being thus heated, are not subject to this difficulty when treated in a 
cylindrical furnace. But small tools of necessity require a different 
method. The distortion is entirely avoided when the heating is done 
in a suitable bath. Lead, because of its high specific gravity, is not so 
well adapted for this purpose as certain others. The tendency is for 
tools to float to the surface, and thus be irregularly heated, unless held 
down by some means. The lead bath, while it has been successfully 
used for hardening high-speed tools, is held at the extremely high tem- 
perature required, with some difficulty. It begins to vaporize at about 
640 degrees C. (1190 F.), and when heated much above that point rapidly 
volatilizes, giving off offensive and irritatingly poisonous fumes. These 
can, however, be conducted away so as to do little harm, if provision 
be made, as already shown, for effectively exhausting from a properly 
designed hood. 



108 HIGH-SPEED STEEL 

There are other disadvantages in using the lead bath at these high 
temperatures, and indeed some disadvantages at any temperature. At 
a white heat the lead oxidizes rapidly, and even when the surface of the 
bath is protected by a thick covering of powdered charcoal, more or less 
of this takes place, the scum rising and floating upon the surface of the 
lead. A much more troublesome thing is the sticking of the lead to the 
surface of tools, and the consequent uneven hardness that results from 
the parts so covered cooling at a rate slightly different from the parts 
of the surface to which no lead adheres. Efforts to prevent this trouble 
only seem to aggravate it or to develop new ones equally objectionable 
or worse. Likewise, impurities in the lead not infrequently damage the 
surface of the tool with which it comes into contact, especially at the 
white heat to which it is subjected in hardening high-speed steel. Holes 
and interstices sometimes remain filled with lead when the tool is with- 
drawn for cooling, and the result is worse even than when flakes of lead 
adhere to the surface. 

Difficulties Overcome by Barium Process. — All these, and other 
difficulties are overcome by the barium chloride bath process. The 
chloride does indeed give off fumes, unless precautions are taken to pre- 
vent; and a thin coating of it adheres to the tool when it is withdrawn 
from the bath. This latter, however, is just what is required in order 
to prevent oxidation while the tool is exposed to the air; and since the 
film is evenly distributed, there is no uneven hardening. It is possible 
also to maintain a more uniform temperature, since the melted barium 
chloride circulates freely, much more so than the heavier lead, so that 
the temperature throughout the bath does not vary sufficiently to be 
taken into account. 

Heating in a fluid is little or no quicker than in an open fire or in a 
good furnace. Evidently, however, if the bath itself is uniformly hot 
throughout, the heating of the tool must be absolutely even. Pro- 
jections cannot be melted down nor burnt before the interior has had 
time to reach the same heat as the outside, since it cannot get hotter 
than the bath, and that is kept uniform at the temperature required 
for the kind of tools in hand. The danger of blistering the surface or 
melting down the corners of a tool put into a white-hot furnace without 
sufficient preheating is entirely obviated. Even if the bath should for 
any reason be at a temperature high enough to damage a delicate tool 
thus suddenly subjected to an intense heat, the barium chloride has a 
melting temperature so high that a relatively cool object plunged into 
the fluid immediately causes a coating of it to solidify around the article. 
The coating of solid barium chloride then protects the enveloped article 
until its temperature rises sufficiently to melt it off. 

Furthermore, even though the actual heating of any given tool pre 
ceed little or no more rapidly, it is possible to gain a great deal of time 



HARDENING — THE BARIUM' CHLORIDE PROCESS 



109 



by the simultaneous heating of a considerable number of tools. A 
basketful of small or medium sized tools can thus be hardened just as 
well, just as certainly, and just as quickly as a single one. It might be 
supposed that tools so heated and quenched, that is in promiscuous 
contact with one another, might vary more or less in hardness. Such 
nevertheless is not the case, all coming out absolutely uniform. 




Fig. 82. A day's work. Good illustration of the various classes of tools to the hardening of which the 
barium process is especially adapted. 

The Furnace and Equipment. — The furnace for hardening by the 
barium chloride process may be of any convenient form which will 
admit the use of a suitable crucible. A vertical gas-fired furnace is 
preferred, one so designed (Fig. 83) that the flames are directed around 
rather than toward the crucible, enveloping it in a whirl of heat which 
is absorbed uniformly over its whole surface. If the flames impinge 
directly upon the crucible, there is danger of holes being melted into it 
when the heat is turned on, before the bath has become fluid and able 
to conduct the heat away rapidly enough. 

The crucible is almost necessarily of graphite. It should rest upon 
fire bricks so disposed upon the floor of the combustion chamber as not 
only to prevent the bottom falling out, but also to allow the flames to cir- 
culate freely about the under portions as well as over the sides. It should 
be so adjusted as to height that the top rises into the circular opening 
in the top plate of the furnace. The crevice may be luted up with fire 
clay or left open, the latter being the preferred method. In this case, 



110 



HIGH-SPEED STEEL 



however, the rim of the crucible must rise well into the furnace top, 
as shown in Fig. 84. 

The supply of air and gas, and the pressure, would be the same as 
for any furnace of similar type but used without the crucible and its 



SEALED 




Fig. 83. Cylindrical gas-fired furnace and crucible 
for use in hardening by the barium chloride 
process. 



Fig. 84. Fitting of crucible into 
Leaving the joint unsealed, as in 
erable method. 



furnace top. 
B, is the pref- 



VALVE I 



'5TOP PIN 



PI J SAFETf VALVE 



2 

DRUM 
<5'P/PE 






y+~ VALVE — ,-,- 
(WATER) %? 




I'PIPE 



Fig. 85. Reducer apparatus for use where air is delivered at a pressure higher than 1 \ or 2 pounds. 
Necessary when using compressed air in gas furnace. Courtesy of E. S. Jackman & Co. 

1. Valve with an adjustable stop or gage on it. 

2. Drum with petcock for draining off the water which appears when the air expands. 

3. Safety pressure valve set for about K pounds to the square inch. 

4. Valve for regulating the supply of air to the furnace. 

5. Fitting to prevent possibility of high-pressure air backing up into gas supply pipe. 



HARDENING — THE BARIUM -CHLORIDE PROCESS 



111 



contained bath. Fig. 85 illustrates a desirable apparatus for reducing 
and regulating the air pressure. In operation valve 1 is opened to the 
stop, which should be set so as to admit just enough air to blow off 
gently safety valve 3 when valve 4 is wide open. The flame is con- 
trolled by valve 4, but valve 1 must always be open when the furnace 
is to be used. 

A good pyrometer should by all means be a part of the furnace equip- 
ment for hardening by this process, so that accurate determinations 
may frequently be made of the thermal condition of the bath. 

It is well also to have a fire-brick cover pivoted at one side so as to 
be easily and quickly swung over the top when desired. It is convenient 
to have a small opening in this cover, which in turn can be closed by 
placing a fire brick over it. The fire 
chamber of course should be vented, 
preferably into a stack. In this case, 
however, it is desirable so to fix the 
exhaust that there is a space between 
the opening from the furnace and the 
pipe or small hood, at which the flame 
from the furnace can be seen emerging. 
By watching this the mixing of gas and 
air can be regulated to a nicety. A 
very small flame indicates perfect com- 
bustion. When no flame is visible, the 
air supply should be reduced; and if 
there is a large flame, too much gas is 
supplied in proportion to the air. The 
flame should be just barely visible. 

Electrically Heated Furnaces. — Elec- 
trically heated furnaces are in successful 
use in some plants, and are stated to 
be economical when used for continu- 
ous runs. In this type of furnace the 
loss of crucibles is practically nothing, 
one lasting continuously for six months 
or more; whereas in a gas-fired furnace 
it lasts scarcely two weeks. It should 
be mentioned, however, that in certain 
hardening plants the electrical furnace 
is not favorably r garded because of the 
apparent tendency toward emphasizing 
the formation of a soft skin at the surface of tools hardened in the barium 
chloride bath. 

In such an electrically heated furnace the electrodes are of very soft 





Fig. 86. Electrically heated barium chloride 
furnace, as used by Ludwig, Loewe & Co., 
Berlin, who were among the first (if in- 
deed not the very first) to make use of 
the barium process for hardening high- 
speed tools. 



112 



HIGH-SPEED STEEL 



low-carbon iron, placed opposite each other inside the crucible, which 
latter is imbedded in a thick layer of asbestos or other non-conductor 




Fig. 87- Electric hardening furnace, switch panel and transformer. 
Courtesy of General Electric Co. 




jQax///ari//:/ecdrodd ~~J. 

7d Transformer 
\ IZZZZ 



To Tramfor/ner 



Fig. 



Method of starting the electrical furnace. 



of heat. This layer in turn is surrounded by a thick wall of refractory 
material like fire clay and other insulating materials, and all are held 
together by a steel or iron jacket. In this way the heat is so completely 



HARDENING — THE BARIUM 'CHLORIDE PROCESS 113 

retained within the furnace that at the end of a day's run the exterior 
is scarcely hot. There are of course the usual accessories, and a con- 
troller for varying the voltage and resistance and thereby the tempera- 
ture. A very low voltage, say from 5 to 60 or 70 volts, is employed in 
operating the furnace, the higher tensions being necessary only at first 
while the Baits are being melted. Thereafter the voltage does not usually 
exceed 25. Alternating current only can be used, the direct current 
setting up electrolysis whereby chlorine is liberated and attacks the 
tools immersed in the bath. The fumes of course also are increased. 

The fusion of the salts mixture is accomplished by moving a supple- 
mental electrode of carbon close to the appropriate iron electrode (Fig. 
88) until the sparking has melted some of the salts, which latter then 
conduct the current. The resistance offered to the current heats and 
melts the adjacent crystals until the movable electrode has established 
a melted stream to the other iron electrode. After this the contents 
of the crucible fuse quite readily. During the melting of course a higher 
tension is required than afterward. With the controller the tempera- 
ture can be regulated to within something like 10 degrees C. In taking the 
temperature, and in hardening also, it is to be remembered that a rela- 
tively thin layer, half an inch or so, at the top of the bath is a little 
cooler than the rest, the difference varying some, but usually being near 
10 to 20 degrees C. 

Methods of Operation. — When starting or renewing the bath, the 
crucible is filled with commercial barium chloride l mixed with a small 
proportion, say about two per cent, of sodium carbonate, commonly 
called soda ash. The two substances must be melted together, other- 
wise, especially if the crystals are used, dangerous explosions are likely 
to occur. The soda ash, in a way which does not seem to have as yet 
been investigated, prevents to a considerable extent the rising of chlorine 
fumes from the bath. These are offensive and very irritating when 
breathed, and also discolor the surfaces of tools with which they come 
into contact. The soda ash seems also to have some other effects as 
yet not well understood. It gradually becomes exhausted, and requires 
renewal from time to time. It must be remembered that in renewing 
it is dangerous to throw the ash into the melted barium chloride. The 
danger is minimized or averted if the ash is mixed with several times its 

1 Barium is one of the small group of alkaline earth metals which includes also cal- 
cium (lime) and strontium. Magnesium likewise is sometimes included in the group. 
Barium never occurs free in Nature, its most common occurrence being in the natural 
compounds heavy spar and witherite, both of which have commercial uses. The metal 
itself has no present use in the arts, though intrinsically it is very interesting. It is 
moderately hard, of a yellowish color, fusible at about 240 degrees C, and burns in the 
air with great brilliancy. Commercial chloride of barium sells in quantity at about 
three cents per pound. It fuses at 890 degrees C. (1635 F.). The chemically pure does 
not melt so readily as the commercial. 



114 HIGH-SPEED STEEL 

own bulk of the chloride before being added to the bath. Care must 
be taken that the proportion does not exceed that mentioned, otherwise 
the temperature of the bath is not so easily regulated. The boiling 
point of the bath seems to be lowered approximately in proportion to the 
excess of soda ash; and since it is very difficult, if indeed it is at all possi- 
sible, to raise the temperature above the boiling point, the tools cannot 
be heated high enough to be properly hardened. The bath should be 
renewed whenever it becomes sluggish. 

The melting should be slow at first. Once well started, however, the 
bath is rapidly brought to the required temperature, which varies more 
or less according to the class of tools to be hardened, as already shown. 
In general, the temperature will be somewhere near, and usually rather 
below, 1200 degrees C. (2200 F.), being raised above that point or lowered 
beyond it as required. The exceedingly high temperatures to which 
roughing tools are raised are unnecessary for the kind of tools to 
which the barium process is best adapted. Those high temperatures are 
sufficient to melt down cutting edges and affect the surface finish of 
tools, and one of the reasons for using the barium process is to avoid 
precisely this thing, or the possibility of it. 

Length of Immersion. — The bath being at. the proper temperature, 
small tools may be immersed and left until they are throughout the same 
temperature as the bath. The time required will necessarily vary accord- 
ing to the size and form of the tools, but in the case of small and regularly 
shaped tools it will range from a few seconds to a minute, or possibly two 
minutes. Larger tools of course require a longer time to become heated 
through; while those of a half inch section, or smaller, should be ready 
in less than a minute. The operator must learn to gage the time by 
actual experience. This is comparatively easy with the barium process, 
for, since the temperature of the bath is no higher than that to which 
the tool is to be raised, the latter is not damaged by remaining in the 
bath for some time longer than would be required merely to heat it 
through uniformly. It is well, nevertheless, not to leave tools in the 
bath for any considerable time longer than actually necessary. 

The Protecting Film — Quenching. — When withdrawn from the melted 
barium chloride, the tool is covered by a thin film, which serves to 
prevent the surface coming into contact with the air. It is this fea- 
ture perhaps more than any other one that gives to the barium chloride 
process its distinctive value. The tool can be quenched in oil without 
having at any time, from the moment the heating began, been exposed 
to oxidation. The coating of barium chloride protects the tool to a con- 
siderable extent also when the cooling takes place in an air blast, though 
it flakes off more or less and leaves spots exposed to the. action of the 
air. The better way is to quench in oil. Dies for drop hammers, and 
tools for other uses where they are subjected to concussions or severe 



HARDENING — THE BARIUM 'CHLORIDE PROCESS 



115 



jarring, are not quenched, as a general thing, but on removal from the 
barium chloride bath are allowed to cool slowly in the air. The film of 
barium chloride protects them from oxidation. 





Fia. 89. 



A tool withdrawn from the bath is covered by a thin film of barium chloride, which protects it 
from oxidation when exposed to the air. 



Preheating Large Tools. — All tools of any considerable size should be 
preheated before being placed in the bath, and in certain cases it is 
desirable that small ones also receive this treatment. Of course, where 
very great attention must be given to the absolute preservation of lines 
and surfaces, large tools also are plunged into the bath without the pre- 
heating. Where this is not absolutely necessary, some time is saved by 
the preheating, for the immersion of a large unwarmed tool of course 
chills the bath so that it is then necessary to restore the temperature to 
the required point. 

Avoidance of Temperature Fluctuation. — This happens also to a much 
less extent when a tool which has been preheated, is plunged into the 
bath, since the temperature of the tool is necessarily considerably below 
that of the bath. Evidently, then, it is desirable that the bath be ample 
enough to minimize fluctuations due to this cause. Small tools of course 
do not have any important influence in changing the temperature, and 
so far as this point is concerned may be put into it without preheating. 
It is very important that the temperature be carefully watched, and 
regulated as may be necessary. The experienced operator of course 
learns to judge very closely by its appearance and behavior whether or 
not all is right, but even he needs to check up his judgment against a 
reliable pyrometer from time to time. The influence of a passing shower 
even, changing the brightness of daylight as it does, is sufficient to make 



116 



HIGH-SPEED STEEL 



error easily possible in judging the temperature by the eye. The oper- 
ator with limited experience must of course be very largely guided by 
the indicator or record, as the case may be. 

Method of Preheating — Saving Time. — Heating tools in this way, pre- 
paratory to their being placed in the barium bath, effects a considerable 
saving in time when many are to be treated. Several are kept in the pre- 
heating furnace or bath and are given the higher heat treatment in turn. 

For preheating, any convenient furnace may be used, though the 
reliability and convenience of the gas oven furnace especially recom- 
mends it for this purpose. The lead bath also is very convenient. 
The heat is carried up to a low red, not above 600 degrees C. (1100 F.), 
and preferably somewhat below this. At this temperature no oxida- 
tion occurs, and it is perfectly safe to raise tools to this point in the gas 
furnace and then to carry them through the air to the barium bath. 
Obviously the preheating temperature must be maintained uniformly 
at the point mentioned, else some of the tools will get hot enough to scale 
more or less. Of course, when the barium process is used in hardening 
tools where this is of no consequence, the temperature in the preheating 
furnace can be as high as desired. 

Quenching Methods. — It has been mentioned already that the air 
blast disintegrates the film of barium chloride which adheres to the tool 
when withdrawn from the bath, and that, it is therefore better to quench 
in oil. For this purpose no special appliances are necessary. The oil 
bath already described in connection with ordinary hardening methods 
serves excellently. The net basket into which small tools can be thrown 
without further attention until they are removed, makes this tank 
particularly convenient for use with the barium process. 

Unimpaired Surfaces — Cleaning. — The oil, like the air blast, disin- 
tegrates the coating of barium chloride investing a tool when taken from 




Fig. 90. When the scales of barium chloride have been brushed off and the oil wiped away, the surface 
of the tool is as clean and bright as before heating. There is no impairment of edges, finish, or color. 

the heating bath. When the scales are brushed away and the oil wiped 
off, the surface is seen to be as smooth and every cutting edge as keen 



HARDENING — THE BARIUM -CHLORIDE PROCESS 117 

and perfect as it was before treatment. Not only is the finish unim- 
paired, but even the color is almost exactly as bright and fresh as when 
the tool was first machined or ground. Even an expert could not tell 
merely by looking at it whether a tool had or had not been hardened. 
It has happened a good many times that purchasers have returned tools 
treated by this process, before trying them, thinking, from their appear- 
ance, that they had not been hardened. 

For cleaning off the scales a wire brush is desirable. If any of the 
barium chloride should stick to the surface or cling to corners and recesses, 
it can be readily softened by immersing the tool in boiling water for a 
short time. The scale then comes off without difficulty. 

Closely Sized Tools. — A number of things are possible * with the barium 
process which were only dreamed of before its development. High 
speed steel taps and threading dies, and tools used for similar purposes, 
have until recently left much to be desired. Almost invariably, when 
hardened by the customary methods, they lose size slightly or have a 
roughened surface which interferes with their perfect working. Further- 
more, the shrinkage is not at all uniform, in some instances varying 
several thousandths of an inch even in tools of the same diameter, by 
reason of imperfectly regulated heating conditions and the inherent 
imperfections of the usual methods when dealing with this class of high- 
speed tools. 

Difficulties Overcome. — The barium process entirely overcomes this 
difficulty. And not only can the size be maintained with almost abso- 
lute uniformity, but the tools can be hardened in such a way that they 
combine the greatest possible cutting powers together with a superior 
toughness of supporting stock, to prevent breakage under the high stresses 
to which they are thus subjected. This, with the circumstance that 
the size is not appreciably altered, that the finish is left perfect, and 
that the keenness of the cutting edges is unimpaired, especially adapts 
it to the hardening of many tools (those already mentioned, as well as 
many other kinds) to the making of which high-speed steel has not 
heretofore seemed well suited. Taps, threading dies, and other tools 
with overhanging teeth or cutting edges which, when properly hardened, 
are likely to break off or crumble, or when let down sufficiently to over- 
come this difficulty are too soft to last long, can have these teeth or 
cutters hardened to any desired extent while the body of the tool remains 
in the annealed condition. 

1 It may be of interest to mention, in this connection, that the barium chloride bath 
is also excellent for hardening carbon steel tools. When so used, potassium chloride 
may be mixed with the barium chloride to form the bath, in the proportion of about 
two to three. The potassium chloride lowers the boiling point of the bath to near the 
temperature required for hardening ordinary steels, and thus reduces the danger of 
over-heating them. 



118 HIGH-SPEED STEEL 

Method for Special Tools. — The method is exceedingly simple. All 
that is necessary is to plunge that part of a tool which is to be hardened, 
into the bath, preferably after the customary preheating, just long 
enough for the teeth or cutting edges to become thoroughly heated 
throughout to the required temperature, and then to withdraw it before 
the stock or body has had time to become heated enough to harden 
when cooled. The tool is then quenched in the usual manner. 

Cautions. — It is to be remembered that heating the exterior of a tool 
only, and then suddenly cooling it, as is required by this method, often 
sets up strains and causes flaws because the outside and inside portions 
have not, in cooling, had time to adjust themselves properly. A little 
care on this point will minimize the difficulty; and the subsequent " tem- 
pering" to which most tools of these classes are subjected, can be made 
to relieve any strains which may have been set up in the hardening. 

Hardening Dies, etc. — Dies, and other tools subjected to repeated 
blows or heavy pressures, can be hardened in a somewhat similar way, 
thus avoiding a trouble which it was not possible, before the develop- 
ment of the barium process, to circumvent — that of dies breaking or 
splitting open. A die may have its face hardened, as the cutters described 
above have their teeth hardened, by this part alone being placed in the 
bath, leaving about half of the body not brought to the high heat. 
This method is of course especially useful in the case of dies with rela- 
tively heavy bodies. Care must be taken, in this case, to move the die 
more or less, according to size, in such a way as to avoid a distinct line 
of demarkation between the hardened and the unhardened portions. 

Methods of Handling the Tools. — Not the least important thing in 
hardening by the barium chloride process is the handling of the tools. 
Tongs with spiked or serrated jaws have been mentioned as essential 
to the handling of high-speed tools during hardening. These are useful 
in handling some kinds of tools in connection with the present process. 
For the most part, however, it is desirable to suspend tools of any con- 
siderable size in the bath by wires, or in baskets. Grids or perforated 
metal plates have been used, though these are not so convenient nor 
so certain. When the wires are used it is of course necessary to take 
precautions to prevent tools slipping off. Once a tool drops to the 
bottom of the bath the operator will have his troubles recovering it. 
Tools with holes through them of course are easily handled by wire 
hooks. 

The baskets may be made of wire netting or of perforated sheet metal. 
Most operators prefer the wire. A rather surprising thing is that neither 
the suspension wires nor the much smaller wire (or the thin sheet metal) 
of which the immersion baskets are made, melt or burn away in the 
intense heat of the bath. The barium chloride seems to preserve the 
metal, for there is very little deterioration in the baskets. 



HARDENING — THE BARIUM CHLORIDE PROCESS 



119 



When a number of tools are thus heated in a basket, the latter is trans- 
ferred with its contents, just as if a single tool were being handled, to the 
oil bath and quenched at one plunge. As previously stated, the con- 
tact of the tools with one another does not at all interfere, as might be 
supposed, with their absolutely uniform hardening. 




Fig. 91. Methods of suspending tools in barium chloride bath. 

Difficulties. — As is the case with other methods of hardening, there 
are some difficulties connected with the operation of the barium process. 
The chlorine fumes, and the discoloration which tools occasionally 



& 



American Machinist, N. F. 

Fig. 92. Pair of tongs for handling dies. 

sustain from them, have been casually referred to. Such chlorination 
does no damage except possibly where tools are carelessly left exposed 
for a considerable time. The exhausting hood and the soda ash in the 
bath, with proper attention, will take care of this difficulty. 

Formation of "Bubbles" or Blisters.— A more troublesome difficulty is 
the formation of " bubbles " or " blisters," and of " pits " on the surface 
of tools under certain conditions. " Bubbles " seem to form under two 
well defined conditions, or at any rate appear to be of two distinct kinds. 
Sometimes a tool which has been preheated, or which was never thor- 
oughly cleaned after annealing, or other heat treatment, is covered with 



120 HIGH-SPEED STEEL 

a thin film, or spotted with flakes, of iron oxide. This apparently melts 
at a temperature lower than that necessary to hardening, and in melting 
collects in droplets on the surface of the tool, to which they firmly 
adhere when cooling takes place. They usually are solid (though 
occasionally hollow), very hard, but do no particular harm, especially 
on rough tools, and may be ground off where grinding is permissible or 
possible — which it is not in case of many tools like taps, forming dies, 
and the like. The remedy, or rather the prevention, lies in greater care 
in preheating, the temperature for this operation being kept well below 
the red at which oxidation begins to take place; and in thoroughly 
cleaning those tools, even though not preheated, which may be coated 
with the iron oxide. 

" Bubbles " or blisters very like those described, but readily brushed 
off after cooling, also are of not infrequent occurrence. They are thought 
to be caused by molten droplets of iron oxide, floating in the bath, com- 
ing into contact with the surface of a tool and attaching themselves to it. 
Since they are so easily removed, and do no harm, no attention need be 
paid to them. 

" Pitting." — Much more troublesome than either of the " bubbles " 
mentioned, is the " pitting " which sometimes takes place. There 
sometimes appears, in this case, to be a melting away of the steel in spots, 
particularly along the edges or in projections from the body of the tool, 
leaving usually a slight hollow which sometimes is accompanied by a 
raised lump as if the metal had melted out and not floated away. More 
usually a " blister " is raised, beneath which a depression or " pit " is 
found. When such " pitting " takes place the tool is ruined and is fit 
only for throwing away or for working down to a smaller size. Investi- 
gation into the cause of this peculiar phenomenon has thrown but little 
light upon it. Inasmuch, however, as it seems rarely to occur, 1 except 
when the very highest temperatures, those not far below the melting 
point of high-speed steel, are used, it is suggested that it may be due to 
the presence in the steel of particles not perfectly homogeneous, which 
fuse at a temperature below the melting point of the homogeneous por- 
tions. No trouble of this sort is likely to be experienced if the tempera- 
ture of the bath is not allowed to rise above 1200 degrees C. (2200 F.) or 
thereabouts. This is amply high for hardening nearly all sorts of tools, 
except those just as well treated by other methods. 

1 Something very similar, if not precisely like this, is of common occurrence when 
tools are heated by other methods, if extremely high heats are put on. 



CHAPTER IX. 

TEMPERING. 

Extreme Hardness not Essential. — Some allusion has been made to 
this peculiarity of high-speed steel, that the fitness of a tool does not 
necessarily depend upon extreme hardness, but upon the very different 
property of red-hardness, by virtue of which it resists the tendency to 
become soft or rub away under stress after having become considerably 
heated either through the heat generated in working or through being 
intentionally heated subsequent to the hardening process. As a matter 
of fact, extreme hardness is not infrequently a detriment to a high-speed 
tool, since it has, generally speaking, brittleness and internal strains 
for its concomitants. The latter are set up by reason of the unequal 
hardening of interior and exterior portions; and the damage they may 
cause has been repeatedly referred to. Only small and rather regularly 
formed tools are measurably free from them after hardening. 

"Letting Down." — It has been likewise shown that brittleness in 
tools whose working parts have overhang to such an extent that there 
is not sufficient backing to prevent crumbling of the cutting edges, is 
ruinous. A special method in connection with the barium chloride 
process has been recommended as in large part overcoming this difficulty. 
Even when this special method is used, however, and always (except as 
hereafter stated) in the case of tools hardened by other methods, it is 
desirable, and usually necessary, to " let down " this hardness and 
relieve the strains by a subsequent treatment, " tempering " or " draw- 
ing the temper." This treatment can be carried to any desired point 
and practically all strains relieved, and the toughness of the overhanging 
portions of tools restored to whatever degree required for maximum 
efficiency. The extent to which the temper should be drawn is deter- 
mined very largely by the nature and use of the tool, as it also is 
in carbon steel tools. About the only tools which are not benefited 
by tempering are those of the heavy lathe and similar types, with 
well supported blunt noses. These are customarily set at work after 
hardenings and grinding, without further treatment. The makers of 
some of the " new " high-speed steels say that tempering is unneces- 
sary for any tools made of those particular steels. Where tools are 
desired to be of extraordinary hardness this would be true whatever 
the steel used. 

121 



122 HIGH-SPEED STEEL 

Tempering not the " Low-Heat " Treatment. — The tempering here 
recommended does not correspond precisely to the low-heat treatment 
of the Taylor-White process, for the temperatures are considerably 
below the minimum limit of the range recommended by them in that 
connection. It corresponds almost exactly with the tempering of carbon 
steels, though the temperatures are, in general, somewhat higher, and 
perhaps maintained rather longer. 

Results with Crude Appliances. — As in forging and in hardening, so 
in tempering, results of a more or less uncertain sort can be obtained 
with very crude appliances, or perhaps with none at all. A forge fire has 
served on occasion, though it must be said, that such crude apparatus 
is not at all conducive to accuracy and uniformity in results. If the 
novice desires to do a little experimenting with no adequate appliances, 
this may be done with small risk by taking a piece of, say, tool holder 
steel, such as is used for light cutting, and heating it until it reaches a 
dark straw color, and then cooling in the oil bath or the air blast, as 
when hardening. A greater degree of softness is obtainable by allowing 
the piece to cool in air; and a still greater by raising the temperature 
until it reaches a green tinge, and then slowly cooling. Some tools are 
bettered by following this treatment by another, in which the tempera- 
ture is raised to a faint red, just perceptible in the dark. 

Exact Temperatures Necessary. — Important changes take place in 
high-speed steels within very narrow limits of temperature, not only 
within the hardening range, but within the tempering range also. And 
while the colors through which the surface of a piece of steel successively 
passes, while being heated, are indicative of the temperatures, it must 
be remembered that colors, especially when so slightly different as are 
most of those commonly named and used in tempering, are not only 
difficult to differentiate, even to keen and experienced eyes, but that 
the judgment concerning them is easily affected by variations in the 
light. The range of colors, as ordinarily used, extends from light straw 
to purple, or from 220 to about 275 degrees C. (425 to 530 F.). It is readily 
seen therefore, that exceeding care must be used in tempering to obtain 
just the required temperature and no higher. In order to do this suit- 
able appliances are requisite. Trying to temper high-speed steel in a 
forge fire, as a regular thing, is folly. 

A Simple Method. — An oven furnace can be used with a moderate 
degree of success, if it be capable of having its temperature regulated 
with extreme nicety and provided with a pyrometer for gaging the same. 
This is little cheaper, if any, than the oil process, though it is available 
where the amount of work is so small as not to warrant the installation 
of an oil furnace in addition to the general utility oven furnace. 

Oven Furnace and Sand Pan. — A better method, recommended by 
several makers of high-speed steel, and giving fairly accurate results when 



TEMPERING 



123 




the temperature is carefully regulated by frequent observations of the 
pyrometer, involves the use of a metal sand pan heated by a suitable 
gas or oil burner (or by other suitable means, for the matter of that), 
large and deep enough to contain an 
ample supply of clean and well dried 
sand. The tools are immersed in the 
sand and brought to the desired tem- 
perature without trouble, if the pyrome- 
ter is frequently read. The method is 
very good also where it is necessary to 
dispense with the use of the latter instru- 
ment, since the temper colors are readily 
observed. 

A satisfactory device, particularly use- 
ful where colors rather than the pyrom- 
eter are relied upon for determining 
the proper tempering heats, consists of 
a metal plate supported in any con- 
venient manner and heated by gas or 
otherwise, as shown in Fig. 93. The 
plate is covered by a sheet metal hood 
or oven. 

Method of Special Alloy Baths. — A 
method sometimes used, where the 
variety of tools is small and it is not desired to provide extensive 
equipment, consists in heating the tools in baths which melt at pre- 
determined temperatures. Care must of course be taken that the baths 
are kept as nearly as possible at the melting point. The difficulty of 
doing this makes the method somewhat uncertain, for a rise of a very 
few degrees is sufficient to give a different result. Any sort of melting 
pot sufficiently large for the tools to be tempered, an alloy which melts 
at the temperature required, and any suitable fire, preferably one that 
can be easily regulated, as a gas or oil burner, is all that is required. 
The tools are placed in the melted alloy and kept there from ten to 
twenty or more minutes, depending upon the size and form, until com- 
pletely and uniformly heated through. They are then allowed to cool 
in air, as is customary in all tempering. 

If the metal does not chill and set around the tool when it is first 
placed in the bath, the temperature is too high, and should be at once 
regulated. It is to be remembered that in order to keep the bath fluid 
it is necessary that the temperature be maintained slightly above the 
melting point. This should be considered when preparing the alloy 
suited to the kind of tools to be tempered, and the mixture so propor- 
tioned that its melting point shall be a few degrees below that which it 



Fig. 93. A tempering plate with sheet- 
metal hood or oven, as used in the 
Crossly Brothers Motor Works. 



124 



HIGH-SPEED STEEL 



is intended to maintain. The obvious disadvantage, further than that 
already indicated, that which very much limits the usefulness of this 
method, is the impossibility of varying accurately the temperature of 
the bath without keeping in stock a considerable number of alloys. 
Where more than one alloy is used it is of course necessary to preserve 
the identity of each in some way so as to avoid mistakes in the selection 
for a given use. 

Composition of Alloys. — It is exceedingly difficult to secure absolute 
precision in the measurement of high temperatures; and the deter- 
mination of the rather moderate ones used in tempering even is usually 
attended with more or less uncertainty. Even when the most perfect 
instruments are used, the personal equation of the observer enters into 
their handling and into the observations. The alloys and baths here 
given melt (or boil, in the case of the linseed oil) at points near enough 
the temperatures given for all practical purposes. The designation of 
colors for the several temperatures given is somewhat arbitrary, for 
color discrimination again is a matter of personal judgment and experi- 
ence, as well as of light conditions, as has been already pointed out. 



TABLE V. 



Parts. 


Temperature. 










Color of Surface of Steel at Tempera- 
tures Given. 


Lead. 


Tin. 


Cent. 


Fahr. 


14 


8 


216 


420 


Very faint yellow. 


15 


8 


221 


430 


Faint yellow. 


16 


8 


229 


440 


Light straw. 


17 


8 


232 


450 


Straw. 


18.5 


8 


238 


460 


Full straw. 


20 


8 


243 


470 


Dark straw. 


24 


8 


249 


480 


Old gold. 


28 


8 


254 


490 


Brown. 


38 


8 


265 


510 


Brown, with purple spots. 


60 


8 


277 


530 


Purple. 


96 


8 


288 


550 


Deep purple. 


200 


8 


293 


560 


Blue. 





— 


302 


575 


Polish blue. 


Boiling lins 


eed oil 


316 


600 


Dark blue. 


Melted lead 




321 


610 


Gray blue. 






332 


630 


Greenish blue. 



Tempering in Oil. — A well-equipped hardening plant will have a 
good oil-tempering furnace. This consists essentially of a tank of 
suitable size and form to contain an ample supply of oil, a furnace 
arrangement for maintaining the temperature at the requisite point, and 
a high heat thermometer, or preferably a pyrometer. Inasmuch as it is 
necessary to regulate the temperature within a very few. degrees, the 
furnace must be of a kind whose heat can be controlled to a nicety. A 
gas furnace is on that account preferred. There should be a basket of 



TEMPERING 



125 



perforated metal or of wire netting, in which tools may be placed for 
immersion. This will facilitate their removal, since all are removed 
with the basket, without any need for 
fishing them out separately. 

Method of Operation. — The basket 
and contained tools may be placed 
in the oil while the latter is still cold, 
though it is better first to bring the 
temperature of the bath up to some- 
thing like 200 degrees C. Since the 
main purpose of tempering is to relieve 
strains, it is well to avoid plunging 





Fig. 94. Good type of furnace for tempering in an 
oil bath. Oil could be used for fuel as readily 



Fig. 95. Cylindrical oil-tempering furnace 
with hood. 



tools into a bath much hotter than this, for to do so would heat the 
projecting and exterior portions so rapidly as to set up new strains 
which then have to be overcome. The gradual heating, allowing the 
heat to penetrate as it rises, softens the exterior portions enough to allow 
a readjustment of the molecules under stress, while at the same time 
it leaves the steel less hard and more tough according as the temperature 
is high or low within the tempering range. 

The temperature of the oil bath is raised to the point requisite to the 
tools in hand, and these are left immersed for some fifteen minutes or 
more, the time depending somewhat upon their size and shape. Large 
tools are to remain in the bath longer than is necessary for small ones. 
The latter are not harmed by remaining in the oil, in case it is desirable 
to temper large and small tools simultaneously. It is to be remem- 



126 



HIGH-SPEED STEEL 



berecl however, that only tools requiring the same degree of heat can be 
tempered at the same time. Large tools may be suspended in the bath 
in any convenient manner. When removed, the tools are allowed to 
cool down in air without further attention. Large cutters and dies 
often are left to cool off in the oil. 

Kind of Oil Required. — The oil used may be any rather heavy kind, 
that best suited being the so-called heavy or black cylinder oil produced 
from petroleum. Tallow is sometimes used. The former can be raised 
without trouble to as high a temperature as is necessary in tempering. 

Electrical Tempering. — Drawing the temper by the heating effect of 
the electric current is possible, though not much practiced commercially. 
The method is useful if the barium process is not available for hardening, 
in the case of such tools as milling cutters and others having a central 
opening and requiring the body to be tough while the cutting edges are 
left well hardened. A vise and mandrel suited to the work in hand are 

+ 




Supply JIain 



Kheostat i 

Tool Under Treatment 



-f- Secondary 



+ Primary j-^ 



A/WWWWW*- 



Fig. 96. Apparatus for tempering milling cutters electrically. 



connected to a circuit and resistance regulator, as in electrical hardening. 
The tool having been slipped over the mandrel, and fitting loosely upon 
it, the current is gradually turned on and the heat brought up to the 
required point. Evidently the central portion of the cutter is first 
heated, and also most heated unless the operation be continued for a 
considerable time; and consequently the outer portions retain their hard- 
ness to a much greater extent than the central, which latter are corre- 
spondingly toughened. It is possible to duplicate very accurately any 
previously adopted degree of temper in tools of the same form and size 
by merely using the same current regulation. Obviously, ' however, the 
process is rather limited in its applications because of the difficulty of 
accurately determining and regulating the temperature of the surfaces 
of tools of various shapes and sizes. The method is an improvement 
upon the simple and well-known expedient of heating tools of the kinds 
mentioned by the insertion of a hot rod, somewhat smaller than the 



TEMPERING 127 

opening in the tool, and whirling the latter until the desired color appears 
upon the surface. 

Importance of Proper Tempering. — Certain makers of high-speed steels 
state that while tempering, after hardening, is desirable in the case of 
their particular steels, it is not essential. The statement is not suffi- 
ciently accurate. Tempering is not essential in the case of any high 
speed steel tools of certain classes, or of any class if only moderately 
effective work be acceptable. The proper tempering of carbon steel 
tools is even more particular than the hardening; and if this is not 
exactly true in the case of high speed steel tools, 1 tempering them to 
suit the requirements of the particular service for which they are designed 
still is highly important. The failure to get desirable results from the 
use of high-speed tools can almost invariably be traced to improper 
hardening or, more likely, improper tempering. It is exceedingly 
important therefore to have at hand suitable data, in order that the 
proper temper, as well as the proper hardening heat, may be given every 
tool. Such data have not heretofore been generally available, each user 
of high-speed tools having to depend almost entirely upon his own 
experience and observation. This is after all what must be depended 
upon in any toolmaking plant; and it is perfectly obvious that some 
system of recording accurately the treatment of particular tools is 
absolutely necessary in order to arrive at determinations in the many 
special cases that arise wherever many tools of various sorts are used. 
This matter will be further considered in a subsequent chapter. 

Tempering Temperatures. — The following data as to tempering tools 
are accurate for practically all good makes of high-speed steel, and cover 
in a general way the range of these tools. 

The temper of high-speed tools is, in general, drawn (when they are 
tempered at all) somewhat farther than is done with carbon steel tools, 
as may be seen below. 

Lathe roughing tools, and indeed all tools for heavy roughing, are 
left untempered. 

Large reamers, and drills with heavy stocks, 230 degrees C. (440 F.), 
equivalent to a light straw surface color. 

Ordinary drills, small reamers, and other tools of the sort necessarily 
having rather light stocks or bodies and subject to considerable torsional 
strains, 240 degrees C. (460 F.), a full straw color. 

Threading dies and taps, 260 degrees C. (490 F.), very dark straw or 
brown-yellow. 

Ordinary milling cutters, and the like, 210 degrees C. (400 F.), faint 
yellow. 

1 Allusion has been already made to the claims advanced by the makers of some 
of the so-called "new" high-speed steels, that these require no letting down or 
tempering. 



128 HIGH-SPEED STEEL 

Punches, stamping or cutting dies, and shear blades, 280 degrees C. 
(530 F.), purple. 

Chisels, snaps, and the like tools subjected to sudden shocks, 300 de- 
grees C. (570 F.), polish blue. 

Woodworking tools of nearly all sorts, 275 to 300 degrees C. (525 to 
625 F.), light purple to greenish blue, according to shape and kind of 
wood to be cut. 

Brass working tools, 20 to 30 degrees C. lower than for iron or steel 
cutting tools of same kind. 



CHAPTER X. 

ANNEALING. 

Advantage in Using Annealed Stock. — It is now customary for makers 
to furnish high speed steel stock annealed, instead of as it comes from 
the hammers or rolls, as formerly, though in most cases the unannealed 
can be had if specially ordered. This is very greatly to the advantage 
of the user, since the bar stock thus becomes available in a variety of 
ways without preparatory treatment, it being, for example, a compara- 
tively easy matter to machine tools from stock, should this be desirable, 
as well as to forge them. The use of annealed steel lessens the need for 
unusual care in the matter of bringing tools out of the hardening treat- 
ment with shanks or necks soft enough to minimize the danger of break- 
age at those points. It is to be noted also that the long annealing at 
the mills gives to the steel a uniformity and freedom from strains which 
otherwise would considerably limit the utility of fools made from it. 
Most high-speed steels, can, by proper annealing, be made nearly or 
quite as soft as ordinary tool steels. The method by which this is 
accomplished at the mills has been briefly described in a former chapter. 

Annealing Furnaces. — Whether because only the unannealed stock 
is at hand, or because during the forging or other processes through 



/Pyrometer 

Stem 




The Engineering Magazine 



Fig. 97. Annealing furnace at works of the Brown & Sharpe Manufacturing Co, 

which it may have passed during the making and prior to the final 
hardening, a tool may have become more or less hard, very likely un- 
evenly, it not infrequently becomes desirable or necessary to anneal 

129 



130 HIGH-SPEED STEEL 

pieces in the toolmaking plant. If much of this is to be done a suitable 
annealing furnace of the necessary capacity of course is requisite. A 
gas fired oven furnace of ample size is most often used, though the slightly 
less convenient coke or anthracite fired furnace also is in all respects 
suitable and satisfactory. An important requirement in design is the 
ability to sustain a continuous high heat for a long time, if necessary. 
For ordinary annealing such as may be expected to be done in an ordinary 
toolmaking plant, even this is not essential, for the heats need not be 
of a duration comparable to that given at the mills. For occasional 
work the ordinary furnaces used in hardening are sufficient. 

Uniformity Essential. — A prime essential in annealing is uniformity in 
the result — a given piece must be annealed to the same extent through- 
out. Obviously, therefore, the heating must be uniform, and it is neces- 
sary that the furnace be such that the heat shall be evenly distributed 
throughout the fire or heating chamber. The coke furnace is espe- 
cially good in this respect, though gas furnaces are now designed with 
muffle or baffle plates, or double floors, so as to accomplish the same 
result. 

Methods of Rapid Annealing. — Quick annealing, especially with but 
indifferent facilities at hand, is not to be encouraged; for though fairly 
good results may sometimes be thus obtained, it must be remembered that 
proper annealing is a process requiring much care and good judgment. 
If necessary to anneal a piece without any of the desirable appliances, 
this may be clone with more or less success by heating slowly in an open 
fire or furnace to a blood red, holding there for some little time, and then 
allowing the heat to die down very gradually, the tool remaining in the 
fire or furnace until entirly cold. The slower the temperature is raised 
and then lowered, the better the annealing. This holds true with all 
methods in general use. If a smith's fire be used, care must be taken 
to make it deep and to cover it up well after the desired heat is reached, 
so it will die down very slowly. It is better to build a hood over the 
fire, resembling that mentioned in an earlier chapter, and to fill this 
up with coke before the fire is allowed to go down. If a gas or coke 
furnace be used, air must be carefully excluded during the cooling, 
to prevent excessive oxidation. The heating will occupy anywhere 
from two hours to ten, according to the size and condition of the piece, 
and the degree of softness required. The heat must thoroughly and 
uniformly penetrate the entire piece. 

Instead of cooling down in the fire or furnace, the tool being annealed 
may be withdrawn and buried in sand, ash, lime, or asbestos of generous 
quantity and previously well heated up, and allowed to cool there. A 
quicker method is sometimes employed, which, however, is not very 
certain, and but partially accomplishes the object. The steel is heated 
to a dull black red and plunged into hot water. The temperature of the 



ANNEALING 



131 




Fig. 



piece must not exceed that indicated, while that of the water must be 
little short of the boiling point. 

Protection from Oxidation. — If possible the steel should be enclosed 
in a muffle, even if nothing better be at hand than a piece of gas pipe, 
and packed closely in green coal dust, coke dust, powdered charcoal, 
or the like substance, to generate a non-oxidizing gas which shall envelop 
the pieces under treatment. Asbestos, ashes, or sand also serve pretty 
well, though usually the surfaces of the annealed tools are less perfect. 
It is much better to have a suitably designed muffle, preferably of cast 
iron and lined with fire brick, for this use. A rectangular box pro- 
vided with a flanged lid (Fig. 98) is excellent for the purpose. The 
flange should fit very loosely into a 
grooved rim projecting from the top 
of the box. The groove is filled with 
sand, fine ash, or fire clay, to exclude 
air. The clay answers this purpose 
rather better than the sand. It is 
well to have one or more small holes 
through the cover for the escape of 
gases; otherwise the clay filling may 
be blown off in places. It is very 
necessary to take precautions for the 

exclusion of hot air (and cold also, for the matter of that), because sur- 
face oxidation of the steel takes place, in that case, frequently to such 
an extent as to impair the uniformity of the subsequent hardening. 

Time and Temperature Required. — The box and contents are then 
placed in the moderately hot furnace and slowly brought to something 
more than a dark red, anywhere above the point at which softening is 
completed, and below that at which recalescence begins, or above 700 de- 
grees C. (1300 F.) and up to near 800 degrees C. (1460 F.), somewhat 
beyond which lies the critical point in heating. 1 This temperature is 
maintained from one to four hours, according to the size of the box and 
of the pieces being treated. The point is to be sure that every piece is 
completely and uniformly heated through. Soaking, that is to say, long 
continued heating, is likely to be injurious, and should be avoided. It 
tends to make the structure of the steel coarse, as it does in the case of 
ordinary steel, increasing at the same time the liability to cracking during 
the subsequent hardening. 

It is of course possible to arrive, by experimentation, at a definite 
time for which given bars or pieces must be heated in order to anneal 
perfectly and without damage to the structure; but in miscellaneous 
work the conditions vary so much that no specific rule can be laid down. 



Pot for annealing. 



1 See the chapter on Nature and Properties. 



132 HIGH-SPEED STEEL 

Only experience can be relied upon as a guide, though the limits above 
mentioned will indicate the approximate range of time within which 
the heating is to be done. It is better, at first, to under-heat rather 
than over-heat (that is, continue the treatment for a shorter rather 
than for a longer time than seems probably necessary), since the anneal- 
ing can be repeated in case it has not been carried far enough. 

Maximum Temperature. — More important still is the maximum 
temperature maintained. If raised considerably above that already 
indicated (800 degrees C. or 1460 F.), the purpose of the treatment is in 
part defeated because near this temperature the changes begin to take 
place which are necessary to hardening; and the steel comes out imper- 
fectly annealed, if indeed not quite hard at times, especially if the 
cooling proceeds less slowly than it should. The temperature may some- 
times, under conditions insuring extremely slow cooling, range a hundred 
or more centigrade degrees higher. Frequent readings of the pyrometer 
are very desirable. 

Cooling. — The heating having proceeded until the steel has been 
completely and evenly hot throughout, the heat is turned off and the 
furnace allowed to cool down very gradually — the slower the better — 
and the contents removed only when quite cool. This requires, under 
the best conditions, several hours. Twelve hours is a short enough 
time; and two or three times as long is much better. Cold air must, 
during this time as well as during the rest of the treatment, be carefully 
excluded from the furnace. 

Prevention of Discoloration. — The surface of high-speed steel so an- 
nealed comes out very well, but usually somewhat discolored. It is 
sometimes desirable to leave the brightness of the surface unimpaired. 
This is accomplished to a moderate extent by placing in the bottom of 
the annealing box a handful of resin and a second handful sifted over the 
top of its contents. A thin black film covers the pieces when taken out. 
This objection is avoided by keeping the contents of the annealing box 
constantly surrounded by an envelope of gas, air being absolutely ex- 
cluded during the whole time. To do this there must be a continuous 
supply of gas passing into the box, which latter is provided at one end 
with a small iron pipe screwed into a suitably threaded hole at one end 
and long enough to extend well outside the furnace. At the end of the 
annealing box opposite the pipe is a small orifice. The box having been 
filled and closed in the regular way, the pipe is connected with a gas 
supply. The jet issuing from the small orifice, after the- air has been 
driven out and the box filled with gas, is lighted and the box placed in 
the furnace to be heated in the customary manner. The gas, very 
little of which is consumed, takes the place of air in the interstices around 
the steel to be annealed, before the heating begins, and completely fills 
them during the entire treatment, so that there is no possibility of even 



ANNEALING 133 

enough oxidation to color the surface of the pieces. The method is 
excellent where it is necessary to anneal finished tools. 

Electrical Annealing. — Experiments have been carried on looking to 
electrical annealing and to bright annealing by immersion in a bath of 
fusible metallic salts, somewhat after the manner of the barium chloride 
process for hardening. Moderately successful results have in some cases 
been obtained; but the methods are not as yet sufficiently developed 
for commercial use. The two methods have also been combined, with 
apparently good results, the salts bath being heated by the passage 
through it of an electric current. 



CHAPTER XI. 
GRINDING. 

Importance of Proper Grinding. — Hardening has been very generally 
emphasized as the one most important operation in the manufacture 
of high speed steel tools — the steel of suitable quality of course being 
granted. In one sense this doubtless is true, for a well-hardened tool 
will do moderately good work even when the remaining operations are 
badly done, or, in the case of some of them, quite omitted. It is equally 
true, nevertheless, that a tool giving maximum service must have 
passed successfully through all the operations necessary to its manufacture. 
These operations, from the bar stock to the finished tool, may be given 
as forging or otherwise forming, hardening, tempering, and grinding. 
Certain of these of course are simultaneous in some cases, as when a 
milling cutter is sharpened before hardening, at the same time it is 
formed. Of these operations, grinding is fully as important as any other, 
the same care and precision being required for the development of the 
highest possibilities in a given tool. As elsewhere in the manufacture 
of high-speed tools, incompetent or careless workmen, or inefficient 
methods, may easily spoil or render defective an expensive tool. It 
seems very certain that a large proportion of such tools, as made and 
used in ordinary practice, are more or less injured by improper grinding. 
The operation is in many places regarded indifferently, and in conse- 
quence there is a serious loss in efficiency. Undoubtedly a good many 
discouraging trials of the new steel turn out badly more on account 
of improper grinding than for any other reason. Of course not every 
tool plant can be equipped with the most approved machinery, and use 
the very best methods in grinding, any more than in the hardening and 
tempering of these tools. But it is to be emphasized that the best 
results can be expected only when efficiency characterizes every detail 
in their manufacture as well as their use. 

Kind of Stone to Use. — Much has been said as to the kind of stone 
best suited to the grinding of high speed steel tools. A good many 
makers of the steels recommend emery, or other composition stones; 
others prefer sandstone, and still others indicate that either may be 
used under suitable conditions. The fact of the matter seems to be 
that any of these several kinds of grinders can be used with satisfactory 
results — if the stone used be selected with reference to the work to be 

134 



GRINDING 



135 



done and the proper conditions be maintained. It does not follow 
that all are equally efficient. The thing to be desired in this respect 
is that the wheel shall grind as rapidly as possible, leave a sufficiently 
smooth finish, and yet not overheat the tool. A coarse and hard wheel 
ordinarily will grind faster than a fine and excessively soft one, say 
like a sandstone. In the case of artificially bonded wheels other than 
sandstone, a coarse, soft stone will cut faster than a fine hard one, the 
softness allowing the grain to break down readily, and thus continually 
to present new cutting grains to the surface being abraded, and the coarse- 
ness allowing large, sharp points to engage the work. For this reason, 
and also because it can be speeded up much faster, an emery wheel can 
be made to grind high-speed steel more rapidly than a sandstone. The 
ease with which artificial stones can be modified in grit and bond to 
meet the various requirements, gives them another advantage. While 
it is probably true that most of the damage suffered during grinding 
high-speed tools occurs when emery wheels are used, it by no means 
follows that the fault necessarily lies in the use of a wheel of this kind. 
As a matter of fact, such troubles usually result from the unintelligent 




Fig. 99. Chips from normal grinding magnified. 
■* Courtesy of the Norton Company. 

use of the wheels. The inexperienced or inattentive operator is likely 
to forge.t that the emery wheel is running at a speed very much greater 
than the sandstone possibly can run, and that in consequence the tool 
pressed against its face is heated up much more quickly. The result 
is likely to be a ruined tool. 

" Glazing " and " Loading " of Stones.— A difficulty frequently met 
with heretofore in the use of these wheels, in grinding high-speed steel, 
has been their tendency to " glaze " and " load," that is, for the cutting 



136 HIGH-SPEED STEEL 

grains at the grinding surface to become worn down smooth and dead 
even, and the pores or interstices in the bonding material to fill up with 
the abraded particles of metal. These two conditions sometimes occur 
separately, and at others together. When they do occur, grinding 
ceases in proportion as the surface of the wheel is more or less glazed 
and loaded. To grind, that is, to " cut," the grit at the surface of the 
wheel must be sharp, not worn down smooth; and the interstices be- 
tween the grains must not be filled up. A grinder is a sort of cutting 
tool. The cutters are the infinite number of sharp grains or grit whose 
angles are exposed at the surface of the wheel. These act individually 
very much like the corner of a broken file in scratching a metallic surface. 
They get behind slight inequalities in the surface being ground, or force 
themselves into the metal, and in either case push off a thread-like fila- 
ment (Fig. 99) whose size depends upon the size of the grit and the pressure 
applied. Evidently there can be no grinding under the conditions just 
stated, that is, where the grit is worn down smooth or the interstices 
of the grinding surface filled up to such an extent that the grit does 
not protrude. In hand grinding the tendency is, when one or both these 
conditions prevail, to press the tool the more firmly against the wheel. 
Since little or no work can be done with the grinding surface in this 
state, the additional pressure serves only to increase enormously the 
friction, and generally to ruin the tool by the sudden heating of its sur- 
face or cutting edge. 

Ruin of Tools in Grinding. — It may seem singular that a high-speed 
tool should be spoiled by any temperature to which it might be raised 
in grinding, for that is of course not comparable to the temperatures 
used in the forging or hardening. The damage comes about in large 
part through the " drawing " of the " temper," and in part through 
" checking " or the formation of surface cracks. Softening of high- 
speed steel, as previously shown, begins at a temperature approximating 
550 degrees C. (1100 F.) and is completed near 700 degrees C. or 1300 F. 
The lower temperatures in this range are easily possible in careless grind- 
ing; and indeed, the higher, corresponding to a low red, has been observed 
at the point of a tool flooded with water. The more frequent injury 
probably is due to the manner in which the frictional heating occurs — 
the sudden rise of temperature in the thin outer skin of the tool face ap- 
plied to the surface of the stone, and consequently its rapid expansion 
without reference to the unheated portion back of and adjacent to it. 
The result is that numerous checks or cracks are formed, more or less 
deep according to the pressure, speed and duration. Under these cir- 
cumstances, if the stone be used wet the trouble is likely to be greatly 
aggravated; for the cold water coming into contact with the heated sur- 
face is almost certain to cause a multitude of checks over the whole 
surface affected. 



GRINDING 137 

Wheels Suited to the Work. — A large part of the trouble, if not the 
whole of it, lies in the use of wheels not suited to the work in hand. It 
is well enough understood that the use of one form and size of lathe tool, 
standardized as much as it may be, for all sorts of jobs and on all kinds 
of material, is not only uneconomical, but exceedingly foolish. Various 
jobs require particular tools, such as are specially adapted to the work 
in hand. Precisely the same thing holds true of grinding wheels. It 
is quite as absurd to use the same stone for finishing brass and for 
sharpening tools; and likewise to use for grinding high-speed tools a 
wheel made for an entirely different class of work. If a stone be used 
which has been properly selected, and which is run under suitable con- 
ditions, there will be no glazing, even if the pressure be excessive. The 
latter condition will but tear up the wheel and overheat the tool the 
faster. 

Wheel for General Use. — It may be said, in general, that the difficulties 
just described arise from the use of a wheel too fine in grit or too hard 
(or close-grained) in bond. Wheels made especially for grinding hard 
carbon steel tools give but moderately good results when used on high- 
speed tools. The grain is too fine, and the grade slightly too hard. 
The ordinary run of high-speed tools such as are used in lathe, planer, 
shaper, boring mill, and the like work, require, for moderately rapid and 
sufficiently smooth grinding, a wheel of quite coarse grain. Mr. Taylor 
recommends for general work a mixture of grits, numbers 24 and 30; 
that is, grit passing through screens with openings respectively 24 and 
30 to the inch. For all tools such as described above, unless intended 
for finishing cuts, a 20-combination is entirely satisfactory, and can well 
be used for all sorts of rough grinding, and even for a good deal of finish 
grinding. It is a mistake to suppose that to produce a fine finish in 
grinding the wheel necessarily must be of a fineness to correspond. 
This is true of soft metals, but not at all of very hard. The smoothness 
of the finish in this case, which includes high-speed steel, depends more 
upon the depth of cut (pressure applied), speed, and softness or open- 
ness of the wheel, than upon the fineness 1 of the grain. 

Wheel for Finishing Tools. — Tools requiring very keen cutting edges, 
like drills, milling cutters, and in fact all fine tools or such as are used 
for finishing cuts properly speaking, need a fine-grained wheel, as well as 
a softer one, to insure the best results — say what corresponds to a 60- 
grain J-grade alundum wheel. For tools intermediate in finishing 

1 It may be mentioned here that the fineness of grain or grit is designated with 
approximate uniformity by makers of these wheels, by use of the numbers correspond- 
ing to the number of holes per inch in the screen used. For indicating "grade," how- 
ever, each maker seems to be a law unto himself and to use a different nomenclature 
— most frequently the letters of the alphabet. Even the very general terms "hard," 
"medium hard," "medium," "soft," and the like, vary more or less as applied by 
different makers. 



138 HIGH-SPEED STEEL 

quality or size between the class just mentioned, and large roughing 
tools, a wheel of grit and hardness (or softness, rather, ) between this and 
that already designated for the roughing tools, is often used. A com- 
bination 20 and 30 is much in favor. It is a matter of great conse- 
quence that the wheel used be just suited to the tools; and for this reason 
it is very desirable that a sufficient variety, not only in form, but in grade 
and grain, be kept on hand, so that each batch of tools can be most eco- 
nomically and perfectly ground. The time required for changing wheels 
is in no wise comparable to that gained and the economy secured as a 
result of the changes. This raises the question of the organization 
of the tool-grinding service, which will be considered in another para- 
graph. To avoid the necessity of truing a wheel each time a change 
is made, it is desirable that each be mounted on its own arbor and 
screwed onto the spindle when required, or attached in some other way 
to secure perfect centering. ' 

Running Speed Important. — The speed of. the wheel should be that 
recommended by the maker. Not "somewhere near" it, but as closely 
approximating it as possible. This is very important, and the general 
disregard of it, the inattention to the maintenance of a suitable running 
speed, in general as rapid as the bond of the wheel will safely permit, is 
responsible for much of the trouble that arises in grinding. Indeed it 
may be said with assurance that practically all grinding troubles arise 
from ignorance of proper conditions, or inattention to them. 

Additional Considerations. — There are other conditions also involved 
in the proper grinding of high-speed tools — and of all classes of work 
likewise, for the matter of that. Evidently, for one thing, the wheel 
must be true; and for another, it must run steadily. To secure the 
latter condition, the machine, whether intended for hand or for auto- 
matic grinding, needs to be strongly built and even massive, and the 
spindles and bearings as large as may be consistent with the size of the 
wheels used. Provision of course must be made for keeping grit out of 
the bearings. It is a great mistake to suppose that any old worn-out 
stand will do, even for rough hand grinding. 

Truing Wheels. — The wheel once properly mounted (between soft metal- 
faced flanges with a diameter at least a third that of the wheel, or at any 
rate with suitable washers between wheel and flanges) in a rigid stand or 
machine, it must be exactly trued by a diamond dresser held firmly in 
position by the tool post or other holding device. Dressing by hand is 
unsatisfactory, and dressers other than the diamond do not yield a suffi- 
ciently good condition of the grinding surface. In truing, the diamond 
must be constantly and thoroughly flooded with water, or it is liable to 
be flattened. But little of the wheel material should be removed — only 
enough so the sound is absolutely even as the dresser passes back and 
forth over its face. Very light pressure, therefore, is required. 



GRINDING 



139 




Fig. 100. Dressing an emery wheel. This method is good enough for many kinds of work, but not for 
accurately grinding high-speed tools. 




Fig. 101. The dresser should be a diamond tool, held firmly in a post, as shown here. 



140 



HIGH-SPEED STEEL 



Automatic or Semi-Automatic Grinding. — Such precision as is here 
indicated of course implies automatic or semi-automatic machine grind- 
ing of tools, and is not essential in rough grinding by hand, though 

certain of the recommendations ob- 
viously apply in this case also. Hand 
grinding evidently has no place in a 
well-regulated shop manufacturing or 
using tools in such quantity as to 
warrant an adequate equipment for 
putting and keeping them in proper 
shape. Nothing is more certain than 
that a large part of the ineffective 





Fig. 102. Walker self-contained floor grinder. 

This grinder has much to commend it where 
hand grinding is permissible. The rotating 
hood forms also a bowl which may be kept filled 
with water, for the collection of dust. Caliper 
■ests, as here shown, are essential in the hand 
grinding of high-speed tools. 



Fig. 103. Yankee drill grinder. Motor-driven and 
entirely self-contained. It is essential in a drill 
grinder that the holder be so swung as to grind 
with correct clearance, as this one does. 



work of tools, and the frequently large loss by breakage common in so 
many shops, is due to improper grinding. A drill with lips ground at 
a guess, one lip sure to be different from the other, as is unavoidably the 
case when it is ground by hand, even by an experienced workman, 



GRINDING 



141 



clearly goes into its work with conditions favorable to breakage and 
with every probability that the holes produced will be imperfect. Mill- 
ing cutters, lathe tools, and the like, of course are from their forms less 
likely to breakage under strains; but inequalities in cutting edges, espe- 
cially so in the teeth of milling cutters, core reamers, and the like, 
inequalities inevitable in hand grinding, very evidently will show up in 
the surfaces they leave behind. Furthermore, they tend to promote 
chattering. It should be obvious, therefore, that hand grinding has no 
place in any well-regulated large shop, except possibly for roughing 
tools down to approximate size, and that the precision above recom- 
mended is none too great to insure the highest efficiency in high-speed 
tools. 

Grinding Equipment. — As to the number and kind of machines to be 
installed, this naturally would depend largely upon the quantity and 




Fig. 104. How the clearance of a drill increases from the periphery toward the center. 
Suppose A and B represent cylinders corresponding in diameters to any two points in the cutting lip of 
a drill, and c d the feed or advance per revolution, for the sake of clearness much exaggerated. The angles 
made by the lines 6 and a then represent the clearance required at the selected points. Courtesy of Wil- 
marth & Mormon Company. 

kinds of tools used. In a shop of any considerable size it is likely that 
at least one drill grinder would be required, preferably one easily adapted 
to the grinding of all sizes used, unless there be work enough to keep 
more than one machine busy. 

Most drill grinders now offered conform to the two prime essentials — 
freedom from vibration, and adjustment for maintaining uniform lip 
angles and curves at the points, for all sizes to be ground. It is of the 
utmost importance in grinding drills that the clearance angles along the 
entire length of the cutting edges be uniform; otherwise the clearance at 
some points will be too great, and at others too slight, as is shown by 
the annexed Fig. 104. In order to accomplish this, the drill holder 
must be so devised as to swing through a curve corresponding to the 
required clearance angle. 



142 



HIGH-SPEED STEEL 



Since lathe and like-shaped took form by far the larger portion of the 
tools in most shops, a universal machine adapted to grinding these tools 
is generally essential. Milling cutters can be ground successfully only in 
a machine designed for the purpose, or by the use of attachments to other 
grinders providing the requisite fittings and movements. In small shops 
such a combination machine, say like the one illustrated at Fig. 107, is 
well calculated to take care of all kinds of work. Some of the more 
expensive universal grinders likewise are now provided with attachments 
permitting the grinding of other than rotary tools (Fig. 107). 




Fig. 105. A universal grinder (Gisholt) designed for sharpening lathe and like tools. All angles can be 
produced with certainty, and by following a chart giving the standards adopted, tools can be redup- 
licated indefinitely. 

It is sometimes desirable to make use of special grinders for special 
forms of tools, whether because of the amount of work to be done or 
the superior adaptation of such machines to the work thus in hand. 
An example of such special machine is a saw grinder and a special reamer 
grinder, illustrated at Figs. 108, 109 and 110. Special devices in the 
nature of jigs can be used to a much greater extent than is now done, in 
grinding not only inserted cutter blades, but other tools and parts. 

Cup wheels, used in common with disc grinders on other forms of tools, 
are required for most rotary cutters, since this shape of wheel allows the 
proper facing and backing off of spiral and other difficult shapes of 
cutters. The cup wheel gives a straight clearance or land instead of a 



GRINDING 



143 




Fig. 106. Wilmarth & Mormon Company yankee drill grinder, with 
attachment for universal grinding. Very desirable in a small shop 
with a considerable range of tool grinding work. 




Fig. 107. In shops using relatively few tools, a grinder resembling this Brown & Sharpe machine is very 
desirable, since it is available for practically all classes of tools, including those of the lathe and planer 



144 



HIGH-SPEED STEEL 




Fig. 108. A special grinder for the Tindel inserted tooth metal saw. Saves frequent readjustment of 
a universal machine used for other purposes. 





Nft^Sfi 




■ ^ m 




l%Jr 




m&» V* V * 


^» ■ 


1 
I 
1 


1 ' Ki ^ 13 


. .^^^r 



Fig. 109. Sharpening a Tindel saw on a Le Blond universal grinder. 



GRINDING 



145 




Fig. 110. Grinding a rose reamer on a special machine. 
This is the economical method of doing such work where many tools of the kind are used. 




Fig. 111. Grinding jig designed by William G. Thumm. Especially adapted for grinding inserted 

cutters for a large face mill. 



146 



HIGH-SPEED STEEL 



curved one, such as is obtained (unless unusual precautions are taken) 
when tools are ground on the periphery of a disc wheel. This method 
of grinding, by the use of cup wheels, therefore not only does not undercut 
the edge, but leaves it in the best possible form and condition for effective 
work and maximum life per grinding. 




Fig. 112. The cup wheel has decided advantages in certain kinds of work, as in edging a shear blade, 
requiring a flat land or surface behind the cutting edge. 

Conditions to be Avoided. — Some grinding machines are provided 
with positive feed devices for forcing the tool against the wheel. There 
is no objection to this arrangement if the feed be light, as already recom- 
mended, and if provision be made at the same time for moving the tool 



GRINDING 



147 



£*,_. 



T 



\f 



/ 



or wheel in such a way that one passes across the face of the other 
to a greater or less extent during the whole time of the grinding. If tool 
and wheel face maintain the same rela- 
tive position, even with a light feed, the 
chances are that they will quickly come 
to fit against each other very closely. 
The cutting face of the wheel then gets 
smooth, the grinding proceeds slowly or 
entirely ceases, and the tool rapidly heats 
up, just as if the wheel were glazed — 
which it sometimes is under these cir- 
cumstances. Such a condition is most 
likely to occur when the face of the 
tool is rather large, and in this case 
especial care is to be observed when 




/ 



grinding With a flat Surface. Grinding Fig. 113. Effect of grinding with disc and 
., » .., ., , . with cup wheels. 

across the lace with the angle of a 

wheel having a V-shaped instead of a band periphery, eliminates this 
trouble, though perhaps it somewhat reduces the rapidity of the work 
and at the same time leaves a face more or less curved according 
to the diameter of the wheel, as is the case always in grinding on the 




Fig. 114. Sellers grinder for flat-face tools. The wheel with a V-shaped periphery has certain 

advantages. 



148 HIGH-SPEED STEEL 

periphery of a wheel. The method makes it possible to flush thoroughly, 
a difficult thing to do in flat grinding. When a relatively large surface 
presses against a wheel surface, very little, if any, fluid gets between; 
so that the purpose of flushing is in large measure defeated. 

Wet vs. Dry Grinding. — As to the respective merits of wet and dry 
grinding it does not seem safe to hazard a square statement. Many 
have found, or think they have found, wet grinding advantageous; and 
many others seem to have a contrary experience. The purpose of wet 
grinding of course is to cool the tool and therefore to allow more rapid 
work; and incidentally to eliminate dust. With suitably hooded ma- 
chines the dust is effectually removed; and it is a question if the 
damage often done tools in wet grinding does not much more than 
offset the possible increased speed. If the amount of water thrown 
against the tool is very large and the stream is closely confined to the 
place where the work is done, there is considerable gain in large work. 
There is, however, the practical difficulty of forcing water between 
wheel and tool surfaces where it can keep the face cool, all the greater 
because the amount should be large, but the speed of delivery slow; 
and it is doubtful under these circumstances if the liability to checking 
by reason of the contact of the water with the at times over-heated sur- 
face does not do more damage than good. However that may be, wet 
grinding is very largely practiced in connection with large and simple 
tools, especially where the surfaces to be ground are more or less round- 
ing rather than flat. On such work as milling cutters, reamers, drills, 
and the like, dry grinding seems preferable; and indeed few machines 
are designed for wet grinding of these types. The sandstone, if used, 
must run wet; and this is a good reason why it is best left alone for 
much, if not all, grinding of high-speed tools. 

Oil for Cooling — Nozzles and Hoods. — Modern emery or composition 
stones are not affected by oil, when well soaked, and do not, so far as 
reported, have their cutting qualities impaired. It would therefore 
seem that if oil were used for flushing in grinding all classes of high 
speed steel tools, all the advantages of wet grinding would be obtained, 
with none of its disadvantages. The very considerable waste from 
" spattering " could no doubt be eliminated by suitably constructed 
nozzles and hoods. All grinders should be hooded anyway; and as for 
nozzles, until recently nobody seems to have thought it worth while to 
use anything other than a piece of pipe. With some attention to these 
points oil grinding would seem to promise much in this new' field. 

Grinding Before Hardening. — Whatever may be the several opinions 
respecting sandstone and emery wheels, and dry or wet grinding of 
hardened tools, the kind so far under consideration, it seems to be pretty 
generally agreed that for pre-grinding, that is, for grinding before harden- 
ing, a dry emery wheel is most satisfactory. With a soft or open and 



GRINDING 



149 



coarse wheel, material can be removed with great rapidity . and without 
danger of harm to the tool. Sometimes the tool is ground while still 
hot from the forging heat; and indeed this is recommended where con- 
venient. It is no disadvantage even though the tool be still red hot. 
The advantage 
ofthuspre-grind- 
ing manifestly is 
that the tool is 
still soft, and the 
reduction is 
much more rapid 
than after it has 
been hardened. 

Metal to be 
Removed in 
Grinding. — The 
finish grinding 
obviously need 
be relatively 
slight. This re- 
fers to the sur- 
face of the tool 
in general; for at 
the cutting edge 
the finish grind- 
ing, when rough 
grinding pre- 
cedes the hard- 
ening process, 
must be severe, 
if the full effi- 
ciency of heavy 
tools is to be de- 
veloped. It is 

a matter of remark among the users of high-speed tools that in 
general they do not work up to their highest possibilities until after 
two or more grindings. The reason is simple. The high hardening 
temperature to which they are subjected affects the sustaining power, 
especially at the cutting edge, where the danger of " burning " the steel 
is greatest. Evidently a tool will dull or break down much more rapidly 
when any portion of the injured skin remains than when this has been 
removed; and quite evidently also the tool must either be ground 
several times in the customary manner, or the burnt portion must be 
removed by a severe single grinding, in order to bring out its full possi- 




Fig. 115. The " Wizard 



nozzle prevents the spattering common when ordinary- 
forms are used. 



150 



HIGH-SPEED STEEL 



bilities at the first use. On lathe, planer, and similar tools, T V mcft is 
ordinarily none too much to grind off the cutting edge the first time; 
and on large tools rather roughly forged, more is desirable. On fine 
cutters with keen edges, hardened at a somewhat lower temperature, 
no such heavy first grinding is necessary. Ordinarily such tools are set 
at work without grinding subsequent to hardening. 

Direction Wheel Should Run. — Carbon steel tools are ground with 
the wheel running toward or from the cutting edge, at the fancy of the 

grinder usually ; and good edges can 
be secured either way — provided, 
in the second case, the burr be 
removed by honing. High-speed 
tools are preferably ground with 
the wheel running against the cut- 
ting edge, most grinders being in 
this way able to get better results. 
It is not desirable that the grinding 
face be run along a cutting edge, 
though in certain cases this may be unavoidable. Revolving cutters, when 
so ground, that is, with the wheel rotating against the cutting edge, need 




Fig. 116. High-speed tools are best ground by re- 
volving the wheel against the cutting edges, 
as show in B above, rather than with the teeth, 
as in A. The former method prevents burring 
and allows faster grinding. The cutter must 
be held firmly against the rest, by hand or 
otherwise. 




Fig. 117. 



Customarily the cutter is held by hand against a guide. Especially when used in taking 
finishing cuts, it is better that the cutter be held in place mechanically. 



to be rigidly held against the tooth rest; otherwise there is likelihood 
that they may be drawn out of proper position by the wheel, and the 
teeth scored and the wheel damaged or even broken. The usual method 



GRINDING 



151 



is to hold the tool by hand against a guide. This is liable to permit 
more or less unsteadiness and consequently eccentricity in the periphery 
of the cutter. Holding and rotating the cutter mechanically is much 
to be preferred, particularly if it is to be used for finishing cuts. 

Amount of Water Required. — It seems scarcely necessary to point out 
that a tool started either wet or dry should be finished without change. 
In hand grinding dipping the partly ground tool into water for cooling 
is almost sure to damage it. In wet grinding the water supply must 
be much more liberal than is usually allowed. The flow need not, and 
indeed should not, be very rapid; but the volume delivered from the 
nozzle must be, for ordinary grinding, enough to flood completely the 
tool — say from five to ten gallons per minute. A discharge area 
equivalent to that of a f inch pipe, therefore, is none too large, and for 
big tools is not large enough. 

Keeping Tools Sharp. — Because it is possible to force high-speed tools 
even when dull, it is a common practice to run them longer without re- 
grinding than is economical — to run them, in fact, until the edge breaks 




Fig. 118. 



Grinders in connection with the stock room. This is a very convenient location for grinders, 
the work being done by those connected with the tool or stock room. 



down or the product passes beyond the limits of required accuracy. 
The maxim " keep your tools sharp " is as applicable in the case of 



152 HIGH-SPEED STEEL 

high-speed as in that of ordinary tools; though the consequences of 
disregarding it are perhaps less noticeable when the tools are used in 
connection with strictly modern machine tools. If used in machines not 
especially designed for them, the observance of the caution is a matter 
of great importance; otherwise the wear on the machine and effect upon 
the work is very marked. Furthermore, if the tool is not ground as 
soon as it begins noticeably to dull, the dulling thereafter proceeds at 
an increasingly rapid rate on account of the machine giving under the 
increased strains and the consequent augmentation of the chatter, which 
latter is at the bottom of most of the wear or breaking down at the cutting 
edge. In the end, therefore, it is better to grind oftener, remove less 
metal per grinding, and keep the tools keen. This will almost wholly 
obviate the need for fettling tools in the forge shop, particularly if they 
have been properly designed in the first place to provide for the removal 
of many successive layers at the cutting end before requiring forging 
to shape again. 

Re-grinding — Finding Cracks. — In re-grinding tools, either because 
dulled or because of damage sustained in a previous grinding, the amount 
of metal removed should be commensurate with the condition of the 
cutting edge or tool surface. If the tool has been damaged by over- 
heating in grinding, the part to be ground away most generally will need 
to be at least T V inch, and may need to be two or three times as deep. 
Checks are exceedingly difficult to discover, and usually pass unnoticed 
until the tool breaks down at work. Mention is made hereafter of a 
method whereby they can usually be detected. 

Land vs. Face Grinding. — When re-dressing a dulled tool it is desirable, 
for the most part, to grind both lip or face, and clearance or back, most 
of the material removed preferably coming from the latter surface. 
As tools of the milling cutter type usually wear, a given depth removed 
from the back will give a result equivalent to that produced by remov- 
ing two or three times as great a depth from the face. Grinding the 
back also serves to preserve perfectly the contour of the cutting pe- 
riphery. The life of such cutters is therefore considerably prolonged in 
this way. 

Tool-Room Organization. — The methods and precision here indicated 
as essential to economical grinding for highest efficiency, imply the 
standardization of the tools used in a shop, as far as possible; and the 
organization of the tool supply on a basis which relegates all grinding to 
a department or to departments suitably equipped for first-class work, 
and manned by operators skilled in that especial work and trained to 
the observance of all details of design in particular tools as well as the 
methods to be followed in the actual grinding operations. The organiza- 
tion of a tool-supply department can be very simple, and indeed should 
be so. The prime requirements are proper equipment and operation, 



GRINDING 



153 




Fig. 119. The difficulties formerly attending the accurate grinding of spiral milling cutters have been 
pretty well eliminated in several recent universal cutter grinders. A cup wheel grinding the land back 
of the cutting edge. 




Fig. 120. An expensive method of grinding high-speed or any other tools, viewed from whatever point. 



154 



HIGH-SPEED STEEL 



ROUND NOSE ROUGHING TOOLS 



i SillERS AG° Imcowi* 



for LATHES * PLANERS. 



u:-. -. -,r NO "••■'- 

SuPinstDiht No 19598 



Blunt Tools, 

roR Cast Iron * Haroer Grades of Steel 



Sharp Tools, 

for Wrought Iron a Softer Grades of Steel. 



To Grino TOP FACE AojuSt Machine as Follows: 



To Grind TOP FACE Aojust Machine as Foll 



ton STRAIGHT TOOLS. 



for STRAIGHT TOOLS. 



RIGHT HAND 



LEFT HAND. 



RIGHT HAND. 



LEFT HANO. 



Horizontal Ancle 



97.°7 



Horizontal Anclc 



97.7: 



Horizontal Ancle 



975 



Horizontal Anclc 



37% 



104' 



Veatical Ancle 



Vertical Anc^e 



112' 



Vertical Ancle 



for BENT TOOLS. 



for BENT TOOLS. 



RIGHT HAND 



LEFT HAND. 



RICHT HAND. 



LEFT HANO. 



Horizontal Ancle 



I03!7 



Horizontal Ancle 



Horizontal Ancle 



107'; 



Horizontal Ancle 



107.'; 



Vertical Ancle 



Vertical Ancle 



Vertical Anclc 



I05T6 



Vertical Angle 



To Grind END FACE Use FORMER (A) and Make Horizontal Ancle or Adjustment 86 
When Face is Finished Index Finger of END GAUGE Should Point as Follows: 



rpr 



Size or Tool 



\ y z 



Size of Tool 



>¥' 



Inoc» Finccr Should Point to 



II 15 



27 



Index Fincfr Shoulo Point to 



10 



Sthaicmt Tool 
Ric>u Hand 




Straight Tool 
Lctt Hano. 



ffiONT R»*t^ _V 




Bent Tool 
Richt Hand 




Bent Tool 
Left Hand. 




Fig. 121. Part of direction sheet used in connection with Sellers' grinder. With a sheet thus showing 
standard forms and angles before him, the tool grinder is able to reproduce exactly a tool edge an 
indefinite number of times. 

as stated; standard designs of tools for practically all jobs, all details 
for each tool being definitely determined and carefully observed; and 
an ample supply of tools, sufficient to permit machine operators to 
replace dull tools without loss of time. The latter are at convenient 
times returned to the supply department in exchange for sharp ones. 
The tools are ground in batches, as these accLimulate, to save too frequent 
changes at the grinder. The man in charge of the grinding, of course, 
is provided with a set of standard samples and a chart indicating the 
precise form and angles for each tool. This being carefully followed, 
the difficulties arising from hand grinding, such as varying angles, 
unsymmetrical cutting edges, improper backing off and relief, and the 
like, are entirely absent, and tools not only work more effectively but 
last a great deal longer. The fixed charges on the investment repre- 
sented in such an equipment and ample tool supply is not comparable 
to the economy effected. The conditions of course apply with equal 
force in the case of ordinary tools; and the method of handling the re- 
grinding would be the same for both. 



CHAPTER XII. 

DETERMINING AND REGULATING TEMPERATURES IN HIGH 
SPEED STEEL TREATMENT. 

Reproducing Determined Conditions. — Guesswork is not consistent 
with modern industrial methods. Rough approximation is uncertain, 
and therefore wasteful. It has, of course, always been true, but only 
in recent years has it come to be well understood, that the physical 
and chemical changes involved in so many productive industries take 
place under definite and constant conditions. Variation in conditions, 
whether it be in burning coal under a boiler, conducting an electric 
current, the heating of a baking kiln, the treatment of a tool, or what 
not, involves variation in the nature or efficiency of the product; and 
in consequence also it involves waste. The conditions of maximum 
effect once definitely determined, it is of the first importance in nearly 
all industrial operations that they be reduplicated within the established 
limits, with certainty and economy. The manufacture of high speed 
steel tools forms no exception; on the other hand the accurate gaging 
and reduplication of temperatures, especially high temperatures, is an 
absolute essential to anything approaching the maximum efficiency 
in tools. 

The Eye not Dependable. — Formerly a prime qualification of a success- 
ful tools mith was the possession of a well-trained eye, the ability to dis- 
criminate sharply the colors through the wide range seen in the heating 
of a piece of steel — this, that he might gage with more or less accuracy 
the heat to which the tools of various steels and for different uses were 
to be raised when hardening or tempering. Not that the color scale had 
for him (usually, at any rate,) any definite relation to specific tempera- 
tures, but rather because it was known to be more or less definitely 
related to the hardness and lasting quality of steel tools, the relation 
depending a good deal upon the particular steel used, and perhaps also 
upon other conditions. No matter how skillful a toolsmith might be, 
however, his tools, carefully made as nearly uniform as might be, still 
turned out varying more or less in quality. As we now know, this of 
course is just what might be expected under the circumstances. Until 
lately nothing was known of the critical or recalescence points in steel, 
the precise location of which in the temperature scale must be known 
before the proper heat for any particular steel can be determined. Even 

155 



156 



HIGH-SPEED STEEL 



if they had been known, their precise location by reference to the colors 
as perceived in a piece of steel by the unaided eye, would have been 
practically impossible. This is due not only to the difficulty of discrim- 
inating between the colors of a radiant body when those colors do not 
vary greatly, but even more to the personal equation of the observer 
and the variation in the conditions under which the observations are 
made. 

Elements Making for Uncertainty. — Not only do persons differ as to 
just what is, say bright red or light yellow, or any other color for the 
matter of that; but in the same person the judgment will vary with 
his freedom from fatigue, his physical condition, and even his mood. 
Furthermore, the light in which colors are seen modifies them to a con- 
siderable extent, so that seen in one part of a shop a piece of steel of a 
given temperature might appear to have one color, while in another 
part of the same shop it might appear several shades different. Even 
in the same spot in a shop the light is bound to vary a good deal accord- 
ing to the cleanness of the window and the condition of the weather 
outside. Of course when artificial light is necessarily used part of the 
time, the trouble is still further accentuated. 

The Personal Equation. — The difficulties arising from the personal 
equation, even in the case of skilled observers, is well seen in a com- 
parison of three well-known color scales: 

TABLE VI. 





_^ 


u 




_^ 


u 




• 


t-i 


Pouillet. 1 


a 

CD 


S3 


Taylor & White. 


a 


£3 


Howe. 


c 

Q3 


si 




O 


fa 




O 

566 


fa 

1050 




u 


fa 


Lowest red 
Dark red 


525 
700 


977 
1292 


Low, dark, or) 
blood red J 


Lowest red vis-) 
ible in dark j 

Lowest red vis- ) 
ible in light ) 

Dull red | 


470 

475 

550 
to 


878 

887 

1022 
to 


Lowest cherry 


800 


1472 


Dark cherry 


635 


1175 


I 1 


625 


1157 


Cherry 


900 


1652 


Cherry, full red 


746 


1375 


Full cherry 


700 


1292 


Bright cherry 


1000 


1832 


Light red 


843 


1550 


Light red 


850 


1562 


Dark orange 


1100 


2012 


Grange 


899 


1650 








Bright orange 


1200 


2192 


Light orange 


941 


1725 


f 


950 


1742 








Yellow 


996 


1825 


Full yellow < 


to 
1000 


to 

1832 








Light yellow 


1079 


1975 


Light yellow 


1050 


1922 


White 


1300 


2372 


White 


1205 


2200 


White 


1150 


2108 


Bright white 2 


1400 
f 1500 


2552 
2732 














Dazzling white 


\ to 
[1600 


to 
2912 















1 Pouillet over seventy-five years ago devised his color scale, which even to this day is quoted as 
authoritative, though his instruments for gaging temperatures were by no means comparable with 
those in use to-day, and his results, or his nomenclature, at any rate, are not very well in accord with 
more recent scales, as may be seen in the table above. 

2 It is impossible, in tool-making practice, to discriminate with any accuracy the hues generally 
designated white. 



REGULATING TEMPERATURES IN HIGH-SPEED STEEL 



157 



Dependence upon the eye for the determination of temperatures, and 
their accurate reproduction, leads to very uncertain, and in the case of 
high-speed steels, rather unsatisfactory results. It is quite as evident 
that in the treatment of a commercial product as expensive as a compli- 
cated tool, particularly when made of a material like high-speed steel, 
which requires for maximum effects even more care than the cheaper 
carbon steel tools, adequate means for temperature gaging and redupli- 
cation are of prime importance. 

Temperature Gaging Devices. — A good many instruments and devices 
have been brought forward for gaging temperatures, especially tempera- 
tures above those for whose measurement the spirit of mercuric ther- 
mometer is available. Those at present in use, which are of value in 
connection with industrial processes, are included in the conspectus 
here presented (Page 158). 

Adaptation of Gage to Purpose. — Not all the instruments included in 
the table (VII) are suitable for use in connection with the treatment of 
steels, and some of them can be used to a limited extent only. Thus the 
mercurial thermometer, when of suitable form, can be used for gaging the 
temperature of the oil tempering bath. When so used it needs to be made 
of specially heavy glass, well annealed, and preferably the tube above 
the mercury filled with an inert gas under great pressure. 

" Sentinel " Pyrometers, or Temperature Cones. — " Sentinel " pyrom- 
eters, or temperature cones, strictly speaking, are not instrumental, for 




Fig. 122. Temperature determining cones, or " sentinel " pyrometers, which melt down or 
fuse when predetermined temperatures are reached. 



there is no scale, and each cone can be used but once. They are made 
of metallic alloys or mixtures or earths and the like, so proportioned that 
when a given cone reaches a predetermined temperature it fuses or 
melts down. They are useful, therefore, in indicating when desired 



158 



HIGH-SPEED STEEL 

TABLE VII. 



Class. 


Principle Involved. 


Types. 


Range 
Centigrade. 


Range 
Fahrenheit. 


Expansion 


Variation in volume 


Gas 


0—1000 


32—1850 




of a substance by 


Mercurial 


-C4— 550 


-100—1025 




change of temper- 


Spirit 


-210— 25 


-350— 75 




ature. 


Pneumatic, gas 


low— 980 


low— 1800 






Metal rod, etc. 


low— 485 


low— 900 






Porcelain (contrac- 










tion) 


low— 1800 


low— 3200 






Water current 


0—1600 


0—2900 






Brown platinum 


0—1600 


0—2900 


Pneumatic 


Flow of gases thru 
small apertures. 


Uehling 


low— 1650 


low— 3000 


Calorimet- 


Relation of specific 


Siemens water py- 






ric 


heat to quantity 
absorbed. 


rometer 


low— 1480 


low— 2700 


Fusion or 


Unequal fusibility 


Seger temperature 






"Sentinel" 


of various metal- 
lic or earthy cones 


cones 


0—2000 


32—3600 


Thermo- 


Current developed 


LeChatelier \ 






electric 


when one junction 
of a thermo-couple 
is at a temperature 
differing from that 
of the other. 


Hoskins [ 
Bristol C 
Price, etc. / 


-180—1650 


-380—3000 


Resistance 


Variation in electri- 


LeChatelier 


lowest 1 


lowest 1 




cal conductivity 




attain-|l200 


attain-|2200 




under changes of 




able J 


able J 




temperature. 








Radiation 


Measurement of heat 
radiated. 


Fery ) 
Bolometer \ 


900— 1600 2 


1650— 2900 2 


Optical 


Variation in luminos- 
ity or wave length. 


Morse — superposi- 
tion of incandes- 
cent filament. 


600—2000' 


1100 — 3600 1 






Le Chatelier mirror 
Fery absorption, 


I 500— 2000 1 


925— 3600 1 






Wanner — all pho- 


900— 1800 1 


1650— 3250 1 






tometric compar- 










ison. 










Mesure & Nouel — 










prismatic 


750— 1000 1 


1400— 1850 1 



1 The upper limits of some of these pyrometers are much higher than those here indicated — in 
some cases, as the Fery radiation instrument, and the bolometer, there is no theoretical higher limit. 
The ranges here given are, so far as data have been obtainable, those within which reasonably ac- 
curate results are to be had in industrial service. Certain of the instruments named are sometimes 
made for laboratory use with higher and lower limits. The Holborn-Kurlbaum instrument is the 
German form of the Morse, and its range is the same. 

2 The bolometer, especially in its improved form, is a laboratory instrument capable of measuring 
infinitesimal changes in temperature, and has an unlimited theoretical range. A change as minute 
as the millionth part of a degree can be measured with it. In the improved form it consists essen- 
tially of a pair of differential platinum thermometers made of very narrow strips of exceedingly thin 
foil, one of which is completely blacked and the other bare, both enclosed in an hermetically sealed 
tube. An indicator of the Callendar type is generally used. 



REGULATING TEMPERATURES IN HIGH-SPEED STEEL 159 

temperatures are reached, and can be made to indicate, by using pairs 
selected for the purpose, the maximum and minimum temperatures 
within which a process or treatment must be carried on. Thus if a tool 
is to be heated to between, say 1025 and 1050 degrees C, two cones, 
one of which fuses at the lower temperature and the other at the higher, 
are placed in the furnace while the heat is going up. When the first cone 
melts down, the tool is introduced. By watching the second cone and 
regulating the furnace when there are signs of its melting, the tem- 
perature can be maintained within the required limits. It is well to 
introduce cones of the first kind from time to time so as to insure keeping 
the temperature above the minimum. This method of course is rather 
tedious, and is not permissible as a regular thing in commercial work. 
The " sentinels " are very useful as a check upon the regular pyrometer, 
and also upon the judgment of the operator when tools are hardened 
without such an instrument. Some sixty different grades are com- 
mercially obtainable, giving a considerable range, from about 590 to 
1975 degrees C. (1095 to 3720 F.). 

" Poker " or Fire-End Pyrometers. — The most usual method of gaging 
temperatures of materials undergoing industrial processes is to insert 
into the furnace, fire chamber, or other containing receptacle, the so- 
called fire end or " poker " of any one of several types of pyrometers, 
the temperature being indicated or recorded at a greater or less distance 
away (in the case of the electrical instruments), as may be expedient. 
In expansion instruments the indicators of course are attached directly 
to the stem, as in the water current and the Brown platinum pyrometers. 
These instruments are based on the same principle, the former having 
its non-platinum parts cooled by a current of water so as to adapt 
it for continuous use. The latter is quite durable, but is not adapted 
for continuous use, the stem or fire end being exposed to the furnace 
heat only long enough to allow the indicator to register the maximum, 
the instrument being withdrawn before the iron frame can be injured or 
the platinum impaired. 

Le Chatelier Type. — Le Chatelier seems to have been the first to per- 
fect an electrical heat gage, applicable to industrial processes requiring 
very high temperatures, in his thermo-couple electric pyrometer; and 
instruments of this type are most frequently used in connection with 
the treatment of high-speed steels. Several different makes are on 
the market, varying in excellence, reliability and endurance. All, 
however, are based on the principle that when one junction of a thermo- 
couple (that is, of a continuous circuit composed of two different kinds 
of conductor) is heated while the other remains at a constant normal 
temperature, a feeble electric current is set up which varies more or less 
regularly according to the materials constituting the thermo-couple, 
with the temperature to which the " hot " junction is exposed. The 



160 



HIGH-SPEED STEEL 



current of course can be measured by means of a delicate galvanometer, 
and the relations between the strength of current and the temperature 




Fig. 123. Le Chatelier fire end inserted in oven furnace. 
The indicator is at any convenient distance. 




Fig. 124. Brown quick-acting platinum pyrometer, for intermittent service. 

of the junction having been determined, the deflections of the galva- 
nometer needle may be converted into temperature indications. Owing 
to the " extra currents " and other disturbing elements found in pairs 
of most materials otherwise suitable for the purpose, and likewise 



REGULATING TEMPERATURES IN HIGH-SPEED STEEL 161 

because of the necessity for elements capable of withstanding extremely- 
high temperatures, the thermo-couple material must be selected and 
manufactured with extreme care. Most often, for the determination of 



rNTERCHANOEABtjE 
MOUIAfl OH tTIUIOHT CONNECTION /S)T 




TERMINAL BOX COVER 



WIRE-CONNECTOR 



Fig. 125. StupakoS (Le Chatelier) pyrometer outfit. Courtesy of Charles Engelhardt, New York. 

such high temperatures as are involved in high speed steel treatment, 
the couple is constituted of platinum and a platinum-rhodium alloy, 
though nickel-chrome steel and other nickel alloys also are used. 

Maximum Temperature Range. — The heat resistance of these elements 
is very high, making it possible to expose the instrument, when made 




Fig. 126. Thermo-couple pyrometer enclosed in steel tube, and indicating instrument. 



in the best form, to temperatures up to 1600 degrees C. (2920 F.) and 
even above, for short periods. This is considerably above any tempera- 
ture required in the making of tools, 1400 degrees C. (2550 F.), or there- 
abouts, being the highest usually required. At these temperatures, 



162 



HIGH-SPEED STEEL 



however, the fire ends deteriorate with greater or less rapidity, and are 
easily broken afterward. They are, in order to prolong their period of 
accuracy and permanency, usually protected by being enclosed within 
porcelain, fire clay or other heat-resisting material (a combination of 
asbestos and carborundum, in the case of the Bristol instrument); but 
these frequently crack and crumble, and it is necessary to check the 
instruments at intervals against standards of known certainty, to in- 



x^ 



-^ 



INEXPENSIVE SUBSTITUTE 

FOR PLATINUM-RHODIUM 

COUPLE 




Fig. 127. Bristol compound fire end. 

sure consistency in the readings, if not accuracy. It is shown hereafter 
that absolute accuracy, that is, the indicating of the absolute tempera- 
ture, is less essential than consistency; and so, if an instrument has 
departed from its calibration, the variation being within reasonable 
limit, allowance can be made for this, provided the extent is known. 
When the departure has reached an amount where the indications no 
longer are reliable, of course the instrument must be discarded. 




Fig. 128. Hoskins pyrometer with exposed couple. 



Recent Thermo-Couple Developments. — A recent development in py- 
rometers of this type consists in making the fire end compound (Fig. 127), 



REGULATING TEMPERATURES IN HIGH-SPEED STEEL 163 



only that portion actually exposed to the high temperature being of 
the precious metals. This reduces the expense of renewals considerably, 
while the readings are sufficiently accurate for the present purpose. 




Fig. 129. Hoskins standard fire end, standard thermo-couple with handle and leads, and new nickel 
sheath thermo-couple complete! The fire end is made of heavy alloy wires twisted and welded. 

Another development is the Hoskins thermo-couple, which is made of 
comparatively inexpensive alloys that withstand the required high heats 




Fig. 130. Application of poker to oven furnace, and Bristol method of 
cold end temperature maintenance. 

apparently indefinitely, while at the same time they are made of wires 
heavy enough to require no protection and to allow of considerable 
rough usage without detriment. The fire end junction being exposed 



164 



HIGH-SPEED STEEL 




directly to the temperature to be measured without the intervention 
of protecting tubes or covers, responds quickly, and there is little or no 
lag in the indication. A modified form of this instru- 
ment has one element in the form of an asbestos- 
wound wire enclosed within and joined to a nickel 
tube which forms the other element. 

Protection of Fire Ends. — It is well enough, and in 
the case of most of these instruments necessary, to 
provide an iron pipe covering, perhaps of ordinary gas 
pipe, closed at the inner end so as to form a well, not 
only for the protection of the fire end, but to prevent 
unnecessary and often detrimental air currents. 

Cold End Temperature Compensation. — Inasmuch 
also as the correct registering of the temperature under 
observation depends upon the "cold" end of the 
couple, that exposed to the normal atmospheric tem- 
perature and near the temperature for which the in- 
strument is calibrated (usually about 25 degrees C. or 
75 F.), that end should be out of the range of direct 
radiation of the furnace, or other sources of tempera- 
ture variations. The Bristol instrument has an ar- 
rangement whereby the cold end is kept near the 

Fig. 131. Section of an , . , 

electrical resistance floor; and in case still greater accuracy is required 
than is thus afforded, a compensator is placed in the 
circuit to preserve the calibration practically correct. Unless the atmos- 
pheric temperature varies considerably from that above given (25 degrees 
C), allowance can be made for it in reading the indicator. This allowance 
is governed by the design of the instrument, and is usually furnished by 
the maker, with the instrument. At least one indicator on the market 
utilizes a multiple scale whereby the allowance is made automatically 
by reading the scale nearest corresponding to the atmospheric tempera- 
ture, as shown by a mercurial thermometer provided for the purpose. 
Theoretically the temperature of the cold end should be at zero; and 
in laboratory work, and in certain industrial operations where much 
refinement is necessary, an " ice bobbin " is utilized for maintaining 
this condition. In ordinary industrial processes, such as steel hardening, 
where the length of the elements is sufficient to allow the cold junction 
to be moderately near the limits already indicated, the slight variations 
due to this cause may be disregarded. 

Electrical Resistance Pyrometer. — The resistance type of electrical 
pyrometer is also used to some extent in hardening high-speed steels, and 
for all temperatures below 850 degrees C. (1600 F.) is perhaps the most 
accurate type, suitable especially where a very open scale is desired. 
It depends for its action upon the variation in the electrical conductivity 



REGULATING TEMPERATURES IN HIGH-SPEED STEEL 165 



of a platinum wire or foil, according to the temperature to which it is 
exposed. This variation is practically constant, and when measured 
by an indicator constructed on the principle of the Wheatstone bridge, 
can be easily reduced to temperature units — or most usually, read off 
directly on a temperature scale to which the indicator 
has been calibrated. The indicators and recorders are 
cumbersome and much more expensive than those for 
thermo-couple pyrometers of the same range. The 
latter are better adapted to measuring high speed steel 
hardening temperatures because the resistance instru- 
ments will not stand exposure to the intense heats 
required, except for very short periods, the maximum 
for such short periods even being only 1200 degrees C. 
(2200 F.). For that matter, it is desirable that neither 
kind be exposed unnecessarily; and especially when 
enclosed in porcelain or similar protective cylinders 
they must be heated up rather gradually. The fire 
ends crumble and deteriorate rapidly enough with 
careful usage. Besides being unsuited for continued 
use at temperatures above 850 degrees C. (1600 F.), 
the cost of the resistance fire ends, as well as of the 
indicators or recorders, is very much higher than that 
of the thermo-couple type. 

Water Current and Uehling Instruments. — Two 
other pyrometers have been used in connection with 
hardening high-speed tools, with good results — the water current and 
the Uehling pneumatic. The latter of these, however, is very expensive 
and has no particular advantage over the electric instruments already 




Fro. 132. Le Chatelier 
resistance pyrometer. 




Fig. 133. Mesure and Nouel optical pyrometer. 
O, ground diffusing glass; P, polarizing nicol; Q, quartz plate; A, analyzer; OL, eyepiece; K, rack 
and pinion; C, graduated circle, calibrated and reduced to temperature scale; L, objective. 

described. Both have all non-platinum parts which are exposed to the 
fire, cooled by the circulation of water through or around them. Their 
accuracy and permanency, therefore, is much greater than that of most 
other forms of fire and temperature gages. 

Fire-End Deterioration — Optical Pyrometry. — The deterioration of 
the fire ends is the weak point in most pyrometers of that type; and 
to obviate the difficulty instruments have been devised which do not 



166 



HIGH-SPEED STEEL 



require having any part directly exposed to the high temperature sought 
to be gaged. These, with one exception, are of the optical type; and 
all utilize the energy of radiant matter transmitted to any convenient 
distance, in the determination of the temperature of the body under 
observation. 

Mesure and Nouel Pyrometer. — Of all the pyrometers adapted to use in 
hardening operations, the Mesure and Nouel (Fig. 133) is perhaps the 
simplest, since it is entirely self-contained and has no delicate parts to get 




K 



Fig. 134. Fe"ry mirror or absorption pyrometer. 
DB, a small telescope with B the eyepiece; E, standard lamp; F, mirror; CCi, absorbing wedges. 

out of order. It utilizes the colored field produced by the polarization of 
light from the object observed, and the accuracy of a temperature reading 
or of its maintenance depends upon the judgment of relative colors, very 
much as when the natural colors of a heated object are viewed by the 
unaided eye. For this reason, among others, it is of material assistance 
only in the hands of a skilled operator, and even such an one cannot be 
sure of any accuracy within fifty or more degrees C. at temperatures 
above 1000 degrees C. 

Photometric Type of Instrument. — The LeChatelier and the Wanner 
optical, and the Fery absorption pyrometer each depends upon a photo- 
metric comparison of the relative brightness of the two halves of the 




Fig. 135. Wanner optical pyrometer. 
A, Nicol analyzer; B, biprism for eliminating images; D, slit through which images are observed; E, eye- 
piece, 2 , lens for focusing image upon.D; O,, objective; P, d-v prism; R, Rochon prism; Si, slit for admis- 
sion of light from standard; S^, slit for admission of light from object observed. 

illuminated field, one half receiving its light from the radiant object, 
the other half from a standard source of light forming- part of the 
instrument. The Le Chatelier instrument utilizes an iris diaphragm for 
regulating the amount of light admitted from the radiant object, in 
combination with a mirror and a standard source of light of known 
intensity, the light from the two sources each covering half the field. 
By adjusting the diaphragm until the two halves are of equal bright- 



REGULATING TEMPERATURES IN HIGH-SPEED STEEL 167 

ness, the temperature can be calculated, or read off directly, from the 
scale attached to the diaphragm. 




Fig. 136. Le Chatelier optical pyrometer. 

Fery uses a system of absorbent wedges for the same purpose, and 
the reading is taken in the same way. The Wanner instrument utilizes, 
in combination with the standard source of light, a system of prisms 
and lenses for polarizing in such a way that by turning the analyzer 
with its attached graduated scale, the two halves of the illuminated 
field, one receiving light from the standard of comparison, and the other 
from the object observed, may be made of the same luminosity and the 
temperature then read off at the scale. All the above pyrometers, 
except the Mesure and Nouel, are quite accurate in the determination 
of relative temperatures within their several ranges. Generally speaking, 
the possible error is less than one per cent, and in some cases only half 
as great. 

Morse Thermo Gage. — Perhaps the most convenient of the optical 
pyrometers which are accurate enough for use in connection with high 
speed steel treatment is the Morse Thermo Gage, made in Europe with 
some slight modification under the name Holborn-Kurlbaum Pyrometer. 
It consists of a tube, furnished with lenses if desired, within which is 
the filament of a small low- voltage electric lamp. In the lamp circuit 
is a rheostat and a milliammeter. In determining the temperature of 
a radiant substance it is observed through the tube, and the current 
passing through the filament is at the same time so regulated through 



168 



HIGH-SPEED STEEL 



the rheostat that the filament disappears against the bright surface 
upon which it is superposed. The current used is indicated by the 
milliammeter, and this can be reduced to terms of temperature; or, 



s y -7_. .--. -. . ■» ■ ■ " 




Fig. 137. The Morse Thermo Gage. 

most usually, the temperature is read directly from the scale. With 
little practice the eye becomes very sensitive to any difference in the 




Fig. 138. The Morse Thermo Gage in use. It may also be used in connection with a portable stand. 



REGULATING TEMPERATURES IN HIGH-SPEED STEEL 



169 



brightness of filament and the object upon which it is superposed, and 
temperatures can without difficulty be read with a possible error not 
exceeding two or three degrees C. With this instrument it i-s possible 
to prearrange the conditions for the required temperature, to know with 
certainty when it is reached, and to reproduce the same indefinitely. 
For the higher temperatures, say above 800 degrees C, absorbent glasses 
are provided for reducing the dazzling brilliancy of the field. With these 
accessories the highest temperatures industrially obtainable can be 
read very accurately. 

Fery Radiation Pyrometer.— The Fery radiation pyrometer combines 
some of the features of the optical instruments, with a delicate thermo- 
couple in the circuit, with a sensitive potential galvanometer whose 




Fig. 139. Fery radiation pyrometer. Section. 
E, eyepiece; F, thermo-couples M, concave mirror with aperture; D, diaphragm; T, binding posts; 

PR, rack and pinion. 

indications may be read in degrees of temperature. It is virtually a 
reflecting telescope, the concave mirror focusing the radiant heat of the 
object under observation upon the " hot " junction of the tiny thermo- 
couple. The instrument is sighted upon the object and focused by a 
rack and pinion at the side. There is also a diaphragm for reducing the 
effective aperture when the instrument is pointed at a very hot object, 
preventing the overheating of the thermo-couple. 

Advantages of Optical Pyrometry. — Optical and radiation pyrometers 
are entirely separate from, and within limits may be at any required 
distance from, the source of the heat to be gaged; so that they are not 
at all affected by even the highest temperatures obtainable. Their 
permanence, therefore, and their reliability, are very great, as compared 
with most other forms. Distance, as is well known, does of course 
affect the energy of radiated heat and light waves; but within the limits 
usually necessitated in the kind of work now under consideration, the 



170 



HIGH-SPEED STEEL 



loss is quite inappreciable. Thus it has been shown with a Fery radi- 
ation pyrometer that the temperature indication of a stream of molten 
steel was precisely the same whether the instrument was at a distance 
of three or sixty feet. 

The comparison lights or filaments, as the case may be, where such are 
required, naturally deteriorate somewhat with long use; but even then 



M/<y : .•'.-, ■.. ' -'■ •'''••' 


tS oS 


ffr**'^ 


■ tfu^ 


$•• * "' ' / [ J 


n 


£%*y.y;:.'' ; '■''■-'"". ;; : .. "" 





Fig. 140. Fery radiation pyrometer in use. 

the falling off in accuracy is surprisingly small. It is of course desirable 
that these, like all other pyrometers, be checked up, compared with 
standards from time to time, and kept properly calibrated. 1 

Calibration for Intended Service. — It must be remembered, in using 
pyrometers of this class, that not all bodies radiate the same amount of 
energy at similar temperatures, and that there are certain definite con- 
ditions under which the indications will be correct for the object observed. 
For the present purpose it is perhaps sufficient to point out that an in- 
strument calibrated for use in gaging the temperature of a furnace 
interior is not adapted, without re-calibration, or, at any rate, without 
taking into account this special factor, for use in investigating the tem- 

1 The Bureau of Standards, U. S. Department of Commerce and Labor, Washington, 
D. C, will for a moderate fee test and calibrate temperature gages when delivered at 
the laboratories for that purpose. 



REGULATING TEMPERATURES IN HIGH-SPEED STEEL 171 

perature of a tool in the open air. The instrument must be calibrated 
for the intended use. Not only this, but it is necessary to take into 
account that these instruments are based upon the laws of radiation from 
a so-called " black body/' whether those radiations have a long (heat) 
or a short (light) wave length; and that unless specially calibrated they 
will give correct readings only when the object under observation approx- 
imates, in its conditions, a " black body " — that is, has its reflecting 
power reduced to a negligible minimum. This is accomplished nearly 
enough, in high speed steel treatment, by observing the tools as they 
lie within a furnace, the temperature of whose fire-clay walls is the same 
as that of the tools, the observation being carried on through a relatively 
small opening in the furnace walls. Under these conditions the contents 
of the furnace no longer are seen as having separate form, their radi- 
ation being practically the same as that from the heated walls; and in 
practice, therefore, it is necessary only to sight the pyrometer into the 
furnace — remembering that the conditions are not well fulfilled unless 
the opening through which the temperature is to be gaged is relatively 
small. It is customary, in order to approximate the conditions still 
more closely, to insert permanently into the furnace a closed porcelain 
or iron tube or well of considerable length compared with the diameter, 
and to sight the instrument directly into the tube. This, of course, 
when the temperature of the furnace interior itself is desired. 

Responsiveness and Discrimination. — The responsiveness and the power 
of discrimination of the Morse and Fery pyrometers especially is remark- 
able, though ability to determine minute changes of course depends 
considerably upon the personality and skill of the observer. Ordinarily, 
at the higher temperatures, a variation of no more than 5 degrees C. can be 
easily detected. The power of discrimination, therefore, is considerably 
finer than the absolute accuracy, which latter depends in part upon 
factors frequently neglected and, as already indicated, may vary from 
one to three per cent at those temperatures. This, however, is a matter 
of comparatively small moment in the hardening of tools, since abso- 
lute temperatures are more or less empirical anyway. In this book, 
for example, there are given certain hardening temperatures for certain 
classes of tools. Obviously, however, these temperatures will vary, to 
some extent, with the kind of steel used, and also with the operator and 
his pyrometer, whether that be of the optical or of some other class. 
The important thing is that the temperature gage shall be consistent 
with itself, and that data shall be recorded which will make it possible to 
reproduce with precision the temperature conditions found experimen- 
tally to yield the highest efficiency in the particular tools treated in an 
establishment. 

Lag. — It must be borne in mind that, in so far as the methods of py- 
rometry here described are used in connection with high speed steel treat- 



172 



HIGH-SPEED STEEL 



ment, or in the treatment of other tools, for the matter of that, the 
temperatures observed or recorded are those of the atmosphere or bath 
surrounding the tools, and not necessarily those of the tools themselves. 
Optical and radiation pyrometers of course can be sighted directly upon 



























































































































































































































































































































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2 4 6 8 10 12 14 16 18 20 22 
The Engineering Magazine 



Fia. 141. How the temperature of the annealing pot interior lags behind that of the furnace. Similarly 
the temperature of the interior of a tool lags behind that of the exterior portions. A, temperature 
of furnace; B, of annealing pot in interior. 

the tools, when contained in a furnace; and " poker " pyrometers are 
to be had with exposed fire ends drawn to fine points which may be 
placed against the surface of the tool under observation and its surface 
temperature in that way be measured directly. Such methods, however, 
are not necessary, and usually are not employed in tool-making. An} r - 
way, the interior temperature of a tool could not be determined in any 
such manner, for the surface and the interior heat conditions could easily 
be different. It is sufficient to remember that time must be given for 
the tool to acquire throughout its mass, or at any rate throughout that 
part to be heated, very nearly the temperature of the furnace or bath. 
The larger the tool, of course the greater the lag. This is particularly 
important in annealing tools packed in boxes and the like, in which case 
the lag may easily be sufficient to prevent proper annealing, even after 
a long heat. The safest procedure when such work is undertaken is. to 
make provision for inserting a pyrometer " poker " into the annealing 
box. A pipe well, such as has been mentioned before, is easily arranged 
and answers the purpose. This would, of course, be so placed relative 
to the regular furnace well, or some other convenient opening, as to 



REGULATING TEMPERATURES IN HIGHSPEED STEEL 173 



permit inserting the " poker " with little trouble and without much 
exposure to the direct heat of the furnace itself. 

Selection of a Pyrometer. — The kind of temperature gage adopted in 
a hardening plant will naturally be largely a matter of personal choice 
and the permissible cost, as well as of the particular work required. 
Where the cost of the installation is not closely limited it will usually 
be desirable to have at least two different types of pyrometer — say an 
optical or radiation, and a thermo-couple; this not only in order that 
one may be used as a check upon the other, but because of the greater 



i Counter Weight 




CZ3i 




The Engineering Magazine 



Fig. 142. Suggestion for use of pyrometer with barium-chloride hardening bath, for which opti- 
cal instruments are not well suited. 

convenience of one or the other for certain kinds of work. The optical 
instrument, for example, has been already said to be unsuited for gaging 
the temperature of the barium bath, unless specially calibrated for that 
purpose. 

Indication at a Distance. — None of the optical instruments, it seems, 
has yet been provided with an indicator capable of being used at a 
distance and automatic in its action. Such an arrangement frequently 
is very desirable; and where the plant is large, the indicator and switch- 
board are important features of the equipment, permitting the super- 
visor of this work to be informed at will of the condition of any or all 
furnaces in operation. This is easily possible with the electrical pyrom- 
eters. Each furnace can be, at small expense, fitted with a " poker " 
capable of being switched into the indicator circuit at will, or connected 
with its own indicator or recorder, as the case may be. In some instances 



174 



HIGH-SPEED STEEL 




Figs. 143 and 144. Pyrometer indicator, switchboard and indicator board showing required temperature 
at each furnace and temperature found. 

The switchboard is shown below. Turning the proper crank sets the pointer at any furnace front to 
correspond with that at the board. An electric bell is rung at the same time to attract the operator's 
attention. The indicator at the furnace is shown in the upper view. The apparatus is that devised and 
used by the Standard Tool Company, Cleveland. 



REGULATING TEMPERATURES IN HIGH-SPEED STEEL 175 

it is desirable that the instrument be in a circuit with an indicator for 
use by the operator, and with a recorder in the office for the use of the 
supervisor and for furnishing permanent, records for future reference. 

A Temperature Regulating System. — A system for observing and 
maintaining temperatures in a large battery of furnaces, something on 
this plan, is in use in at least one large commercial tool-making plant. 
Each furnace, of whatever kind, is provided with a thermo-couple 
" poker," and all are wired to a switchboard, from which each is in turn 
cut into the circuit of the indicator (a recorder also could be in the 
circuit, if proper provision were made) and its temperature observed 
by the person attending to this. If not at the standard temperature 
required in the work then in hand, that is to say, if more than five 
degrees off, a crank is turned which at the same time indicates the 
temperature upon the board above the gage and upon an indicator 
board placed immediately in front of the furnace. The operator, 
warned by a bell, notes the temperature and regulates the furance 
accordingly. The indicator boards are made so that the center line 
always shows the standard temperature required for the work being 
done. This arrangement does away with the need for separate indicat- 
ing instruments for all the furnaces, but obviously requires the con- 
tinuous services of some one to attend to the matter of temperature 
regulation alone. It has the further advantage of relieving the furnace 
operator of the distraction occasioned by frequent readings of the pyrom- 
eter when he has to do this himself. In a small plant such an arrange- 
ment of course is not feasible, and some simpler means are necessary. 
In general, one indicator is sufficient for a small plant, though it is very 
desirable that a recording indicator be also a part of the installation — 
both, of course, designed and calibrated for the pyrometer used. These 
can, if desired, be fitted with alarm contacts capable of being set for 
any required maximum and minimum temperatures. The indicator or 
recorder boom, on passing the contact, automatically rings a bell at short 
intervals as long as the temperature is outside the limits set. Such a 
device will result in a much closer regulation, usually, where it is neces- 
sary to work very near to a given temperature. 

Value and Forms of Records. — Records of this sort are more important 
than might at first be thought. It is a well-established fact that any 
operator, whether working on high-speed tools, firing a steam boiler, 
or at any other work requiring the maintenance of uniform temperatures, 
will more carefully regulate his furnace and take greater care to preserve 
uniformity if he have a continuous record staring him in the face and 
constantly reminding him of departures from the required standard, 
than he will without such a record, even if he have an indicator before 
him which can be consulted at will. It is in the study of conditions, 
however, and the determination of those most suitable for the particular 



176 



HIGH-SPEED STEEL 




Fig. 145. Thread recorder in its case. 




Fig. 146. Bristol laboratory electric furnace with recording electric pyrometer. A, furnace; B, ice Jar 
for cold end; C, recorder chart; D, rhesotat; E, switch and fuses; F, socket. 



REGULATING TEMPERATURES IN HIGH-SPEED STEEL 177 

work in hand — a study which should precede, and upon which the work- 
ing out of each separate problem in high-speed tool-making should be 
contingent — that the recorder is most useful and necessary. Take the 
matter of ascertaining the critical point of a given steel, which should 
by all means (if not already • certainly known) be done before under- 
taking to make tools from it. The curve can, of course, be plotted from 
frequent readings of the indicator; but it is much more conveniently and 
accurately made by an automatic recorder, which is dependent upon no 
personal equation of the observer. The record so made (there should 
naturally be more than one, to insure precision) then serves as a basis 
for subsequent heat treatments. The form of the record is not very 
material, though one with rectangular co-orclina,tes (Fig. 145) is more 
conveniently read than one with curved co-ordinates (Fig. 146). The 
latter form usually is simpler in its mechanism. 

Ascertaining Critical Points. — The critical points of a steel can be 
easily ascertained by heating it in an ordinary furnace suitable for 
hardening, though it is frequently more convenient to do this in the 
office or laboratory with a small electric or gas furnace. The former, 
all things considered, is the cleanest and most convenient. It can be 
connected to an ordinary lamp socket at the operator's desk, if desired. 
The pyrometer " poker " for use in determining the recalescent and 
decalescent (critical) points, whatever the furnace used, is preferably 
of a special form, which may be inserted into a hole drilled into the center 
of the specimen piece of steel and firmly held there, or flattened so as to 
be clamped tightly between two pieces of the steel, these being held 
together by dogs or screws, preferably the latter. A recorder is not 
only more convenient in connection with this apparatus, but, as already 
pointed out above, is almost necessary in making a permanent prelim- 
inary record for future reference. 



CHAPTER XIII. 

SOME MISCELLANEOUS OBSERVATIONS ON THE MAKING 
OF HIGH SPEED STEEL TOOLS. 

Industry and the Scientific Method. — The collection and orderly preser- 
vation of data as a basis for subsequent rational deduction and intelli- 
gent procedure has long been considered essential to scientific method; 
and now it is coming to be pretty generally understood that the scientific 



Tool naine- 



-Size_ 



TOOL RECORD. 
No._ 



For piece No.. 



-Operation No. 



-Dept.- 



Steel- 



Critical point- 



Analysis 

-Deterniined- 



Forging Temp 

Hardening Temp 

Tempering Temp. 

Ground before hardening 
Date Finished 



-Forge No. — 
.Furnace No— 
-Furnace No._ 



-Smith- 



-Hardened by_ 
-Tempered by_ 



-Finish grinding by_ 
-Ckecked by 



Memoranda:. 



(Signed)- 



Fig. 147. Form for preserving data requisite in the duplication of tools. 

method is also the successful business method, whether the end sought 
be the perfection of technical processes or the organization of a business 
system. The preservation of appropriate data as a guide to the produc- 
tion of superior high speed steel tools by the simplest efficient methods, 
therefore, should need no arguing. The sneer of the small man in a small 
place, at " red tape " and " overrefinement, " is not nearly so much 

178 



OBSERVATIONS ON MAKING HIGH-SPEED TOOLS 179 

heard as formerly; and properly so, especially in connection with the 
manipulation of the new steels. The question is not as to the keeping 
of data, but as to the kind to be kept. 

Kind of Data Needful. — Within moderately well-established limits 
the precise treatment best calculated to develop the highest efficiency 
in a tool intended for a special purpose is found usually by the " cut 
and try " method. It is desirable, therefore, that besides the record 
of the performance of the tool, there should be data showing the precise 



DIRECTIONS TO TOOLMAKERS. 
1, Lot No 



2. Kind of tools. 

3. Steel 



4. Class of work- 



5. Hardening furnace 

6. Temperature 

7. Method of cooling 

8. Temperature of bath- 



9. Method of tempering- 
10. Furnace 



11. Temperature- 



12. Memoranda:- 



Completed_ 



(Signed), 



Fig 148. Card with directions, accompanying order for tools. 

conditions in the treatment of the tool while in process of manufacture. 
These conditions are comprehended in the form shown herewith (Fig.147). 
Once definitely known, the conditions can then be varied from time to 
time, as may be indicated by the results obtained from the tool at work. 
Obviously when a set of conditions is found which yield just the proper 
excellence, it is necessary only to duplicate them. These conditions 



180 HIGH-SPEED STEEL 

will then be definitely indicated in the directions (Fig. 148) accom- 
panying each subsequent lot of tools of the kind. It will be understood, 
of course, that there is small value in such data and directions unless 
the tool manufacturing plant is equipped and manned so as to take 
advantage of the information collected and furnished; that is, unless 
the plant has a variety of furnaces and other appliances suitable for 
obtaining accurate information as to conditions and for meeting the re- 
quirements indicated upon the direction cards. 

Hardness Test of no Value. — Time spent in experimenting intelli- 
gently — that is, experimenting with adequate appliances, materials and 
data — to fit the tool most nearly to its work, to give it that treatment 
which will produce the highest attainable efficiency in its special work, 
is profitably spent. Of the elements involved in tool efficiency, hardness 
and temper formerly were considered the most important considera- 
tions in design, conditions of use being little regarded. The intelli- 
gent making of high-speed tools, of course, involves a consideration 
of all these, and of other elements, giving to hardness or temper its 
appropriate place. The extreme hardness of many of these tools has 
frequently led to the inference that a tool had been properly treated if 
only it came out very hard, so hard that a good file would not "touch " 
it. It has been shown elsewhere that hardness is no certain test at all 
of the efficiency of a high-speed tool; that while extreme hardness is 
desirable in certain classes of work (cutting very refractory stock, for 
instance), in others it not only is unnecessary, but perhaps even unde- 
sirable. As a matter of fact, the largest users of the best makes of high- 
speed steel find that for many purposes tools do the best work and give 
the most efficient service when soft enough not only to be " touched " 
by a good file, but so soft that it will " take hold." However that may 
.be, the file test for high-speed tools is quite valueless, even in those 
cases where it is desirable that the degree of hardness be determined. 
Such tests, to be of value, would require that the files used be absolutely 
uniform in temper. Even the best of files, however, vary more or less 
in temper and hardness; and a tool passed as hard enough when tested 
by one file, might easily fail to pass the test when tried by another 
presumably of the same temper. 

There are now available several pretty accurate tests for hardness, 
none of which (for reasons just assigned) are of much practical value in 
making high-speed tools. The only real test of such a tool is the work 
it will do under the best practicable conditions. The best conditions 
of treatment once determined and made a matter of record, the same 
quality can be indefinitely reproduced. 

Allowance for Reduction of Size, etc. — The necessity for using larger 
sizes of stock for high-speed lathe and similar tools is considered else- 
where (chapter on Design). Usually it is of no particular importance, 



OBSERVATIONS ON MAKING HIGH-SPEED TOOLS 181 

in tools of this type, whether the stock is exactly sized or not, so long 
as there is enough material to withstand the enormous strains and pre- 
vent vibration, and consequently inferior and inaccurately sized work. 
In other types of tools, however, as in drills and mills, it is necessary 
to take into consideration, in ordering stock, that an allowance must be 
made for the burnt skin which must be removed in making tools of this 
sort. While the effect on high-speed steel is apparently much less 
marked than in the case of carbon steels, nevertheless the long con- 
tinued high heat in annealing affects the surface of bars enough to make 
it necessary to remove the same to a depth varying more or less accord- 
ing to the size of the bar. In stock above an inch in section an eighth 
of an inch should be added to the required size. In larger sizes of stock 
the proportionate allowance decreases rapidly. 

Shrinkage in Fine Tools.— The allowance for shrinkage in finely sized 
tools during the hardening process, of course, is a different matter, the 
allowance being very minute, and generally unnecessary if the hardening 
be carefully done, particularly if done by the barium chloride process. 
Loss in size almost invariably is the result of exposure to the air while 
the tool is very hot. The loss due to actual shrinkage is so small, except 
in large tools, as to be scarcely appreciable and is usually negligible — 
when treated as just suggested. If the hardening is done by the custom- 
ary methods a slight allowance is possibly desirable in the case of certain 
tools — say in the arbor holes in milling cutters, the diameter of taps, 
and the like. With care in hardening, even by the customary processes, 
the variation in a diameter of an inch, or thereabouts, will scarcely 
exceed 0.005 inch, and more likely will be less, though indeed it may be 
as great as 0.01, and even more. It depends so much upon the care 
exercised and the method employed. It should scarcely need adding 
that the holes in all mills intended for very accurate work require to be 
ground after the hardening, the mills having been first carefully centered 
in a chuck. 

Rough Surfaces — Prevention. — It may be added also that apparent 
variation in the size of tools like threading-dies and taps, and other tools 
which cannot be ground after hardening, is frequently only the effects 
of the roughening of the surface during the treatment. The barium 
process overcomes this difficulty entirely, unless, as usually is the case, 
it is present before the hardening. Generally this roughness arises from 
the method of cutting the threads or other teeth, as the case may 
be. Such threads or teeth are best, and of course most quickly, cut 
by milling them, lubricating the cutter with thin oil. Next to this it is 
best to rough out the threads with a chaser, as close to size as may be, 
without lubricant; and then to re-cut or finish with a single-point tool 
held in a spring-thread holder, the threads being kept lightly lubricated 
with very thin oil. To compensate for the slight roughness often present 



182 HIGH-SPEED STEEL 

in high-speed tools of this class, it is customary to give rather more relief 
than in the case of those made of ordinary steel. The increased relief 
minimizes the lodging of particles of steel in the surface of the cutter 
behind the cutting edge, which, acting as cutters themselves, sometimes 
very appreciably increase the cut. 

Securing Smoothness in Drill Flutes. — Extreme smoothness is a desir- 
able quality in high-speed drills also. It seems impossible to obtain, 
by present methods of cutting, a smoothness of surface like that obtain- 
able in carbon steel drills; and on this account the flutes usually are 
polished. If the hardening is by the barium process the polishing may 
be done before hardening, for that process leaves the surface absolutely 
unimpaired. 

Continuity of Structure Desirable. — Though the early method of econo- 
mizing in steel by using tool-holder stock rather than making the entire 
tool of high-speed steel, in the case of those tools whose cutting edges 
or points work without intermittence, as those used for turning, planing, 
and the like operations, is criticised elsewhere, the substance of the 
criticism will bear repeating here. A characteristic of the operation 
of high-speed tools at high speed is the rapid generation of heat at 
the cutting edge. In the case of milling cutters and the like tools 
this is of small consequence, because the cutters are intimately attached 
to a relatively large mass of metal which allows the heat to be conducted 
away very well. Furthermore, the cutters work intermittently, each for 
a very brief space of time, and for the remainder of the revolution are 
exposed to the air and cooled by it. The cutting edges are not allowed, 
therefore, to get exceedingly hot, as is the case with the edge of a turn- 
ing tool run at the same speed. It is necessary that the body of such a 
turning (or similar) tool be large enough to conduct away a considerable 
portion of the heat generated at the cutting edge; and in order to do 
this effectively the tool must be continuous; that is, there must be no 
appreciable interval between the part of the tool which does the cutting 
and the body from which the heat is radiated for the most part, as there 
is ordinarily when a small piece of steel is held in a tool holder. There 
are indeed tool holders which minimize this difficulty; but even these 
are not satisfactory in large sizes. 

Welding High-Speed to Carbon Steel. — From the first, methods were 
sought whereby high-speed steel cutting points could be intimately com- 
bined with tool bodies of ordinary and much cheaper steels. For the 
most part the methods tried were ineffective. Welding the two kinds 
of steel by the customary method has never been found practicable. 
The reasons are not well understood. The disinclination of the two 
steels to unite probably is due to a difference in their coefficients of 
expansion, that of high-speed steel being relatively low. There is, how- 
ever, no trouble in brazing them together; and when this does not 



OBSERVATIONS ON MAKING HIGH-SPEED TOOLS 



183 



involve placing a great strain upon the brazed joint, the method does 
very well. Obviously the cutters are hardened before being brazed into 
place. 

Brazed Cutting Edges. — A successful example of such a combination 
is a lathe or a planer tool, Fig. 149, made with practically no forging and 
with a relatively thin plate of high-speed steel brazed to the front and top 
to form the cutting edge. Rose and other forms of reamers and mills have 




Mtcmrteity NY 



Fig. 149. A planer roughing tool with stock made of machinery steel and cutting edge of a relatively 
thin strip of high-speed steel brazed to the supporting stock. In use regularly in shops of the 
Lodge Shipley Machine Tool Company. 

been made in a similar way, the body of machinery steel being machined 
with recesses for high-speed blades which are brazed into place. Such 
tools have been in use for several years and with excellent satisfaction. 
The latter especially are as good as if of solid high-speed steel, except 
when it is essential that they be re-annealed or re-hardened — which 
need not usually be the case. 

Electrical and Autogenous Welding Practicable. — Almost as soon as 
the new steels made their appearance the writer suggested and demon- 
strated the possibility and feasibility of welding electrically and au- 
togenously a high-speed cutting point to a machinery steel tool body, 




Fig. 150. Welding a high speed steel cutting end to a machinery steel stock. The parts, the welded 
tool with bur, and the tool with bur ground off, are shown. Courtesy of Thomson Electric Welding 
Company. 

the latter of such proportions, of course, as to give the requisite strength 
to the tool. Such tools conform to the requirement of being perfectly 
continuous, and the weld is practically as strong as the rest of the tool. 
It is feasible to forge the end to any required shape, as if the entire tool 



184 



HIGH-SPEED STEEL 



were of high-speed steel; and since in hardening only the nose is heated 
to the high heat anyway, the machinery or tool steel body is in nowise 
impaired. The high speed steel part should extend back as far as the 
hardening heat is likely to go. 

Method of Electrical Welding. — The method of electrical welding, as 
used in this connection, is exceedingly simple. The two pieces to be 
welded are attached to the terminals of a circuit of suitable tension, and 
the edges brought together. The resistance to the passage of the current 
offered by the imperfect contact sets up enough heat to melt the metal 
and forms a perfectly homogeneous junction. The autogenous (oxygen 
or acetylene blowpipe) method is almost as simple. The flame is directed 
into the crevice where the two pieces are brought together, and melts the 
adjacent metal so as to form also a homogeneous joint. 

A Different Method. — Another method (patented) recently brought for- 
ward, somewhat resembling brazing, is asserted to give a joint fully as 
strong as the rest of the tool. A thin film of copper is placed along 
the line of the joint, and the parts to be welded are surrounded by a 
reducing compound and then placed in a furnace raised to a temperature 
of about 1200 degrees C. (2200 F.). The copper flows freely into the 
interstices and is said to produce actual cohesion between the adjacent 
molecules, making a perfect joint, so strong that a fracture will follow a 
new break rather than pass through the joint. 

Availability of Welded Tools. — These methods are available for all 
classes of tools conveniently made in part of high-speed and in part of 

machinery steel or other materials. 
Reamer and mill blades, die faces, 
shear blades, back knives, and the 
like, all are readily welded to sup- 
porting forms or backs, and make 
tools quite as efficient as if of 
solid high-speed steel — and gener- 
ally much more so than if the 
cutters or faces were attached by 
screws, bolts, rivets or similar 
methods. Long shank and exten- 
sion drills, reamers, and the like, 
can readily have the cutting parts 
of high-speed steel and the shanks 
of cheaper steel. The processes, 
especially the electrical, are avail- 
able also for the repair of broken 
tools, many of which can thus be saved for further use. The repairing 
may involve the welding of the broken parts, or the replacing of one of 
them by a new, as may be most expedient. 






Fig. 151. A boring tool repaired by electric welding 
process. Courtesy of Thomson Electric Welding Co. 



OBSERVATIONS ON MAKING HIGH-SPEED TOOLS 185 

Cutting Bar Stock, Sawing, etc. — Only an expert can nick and break 
high-speed steel from the bar without damage to the structure adja- 
cent to the fracture — and even an expert cannot be sure of doing so. 
The only safe way, where the end is to be used for working purposes, 
is to cut the bar. The circular saw is most frequently used, though a 
band saw is preferred for cutting bundles of small stock. Small bars 
can readily be cut in bundles — if held very rigidly. The saws obviously 
should themselves be of high-speed steel. Complaints have been made 
that it is impossible to saw these steels. The complaints probably 
originated in the use of improperly hardened saws; for there is no difficulty 
whatever in cutting them with suitable saws. A singular but most 
effective method has been lately employed to some extent. It consists 
in the use of a highly speeded disc of tough steel. When an unused disc 
is first forced against the high-speed steel, the disc does not take hold 
well; but after being run in contact with the high-speed steel for a time, 
it cuts perfectly and rapidly, leaving a clean, burless kerf. The disc 
may be of any steel tough enough to withstand the tremendous cen- 
trifugal and other stresses set up by the pressure and the terrific speed 
required. Just why such a disc cuts is not sufficiently explained. The 
periphery is usually found studded with particles of the steel being cut, 
and the " sawdust " appears to be the result of true cutting. The 
intense heat generated, the display of fiery sparks, the bright corona, 
the roaring attending the disc's eating its way through the bar — all 
these together are likely to cause some alarm at first. 

Detecting Fine Cracks. — Fine cracks in tools are difficult to discover. 
Even the microscope often fails to disclose them. Generally they can 
be detected by the very simple expedient of moistening the suspected 
surface with petroleum, rubbing clean, and then wiping off with chalk. 
Some petroleum enters the cracks and afterwards sweats out, moistening 
the overlying chalk. The nature and extent of the cracks are thus 
rendered visible. This frequently is of great importance in testing lots 
of high speed steel tools. 

Re-making Worn Tools. — Tools which have worn down so as to be 
useless can usually, when made of solid high-speed steel, be forged or 
machined down and worked up into tools of smaller size, if ordinary care 
be exercised. It is necessary always to re-anneal prior to attempting 
to machine such old tools; and it is desirable also to do it in case of 
forging them to smaller shapes. In passing, it might be mentioned also 
that re-annealing is desirable after machining and before hardening all 
sorts of intricately shaped tools, in order to relieve any possible machine- 
caused strains. 

In re-forging high-speed tools, whether for reduction in size or merely 
in re-fettling, it is desirable that they be heated up rather slowly at first 
They should not be thrust cold into a very hot fire. 



CHAPTER XIV. 

RANGE OF UTILITY OF HIGH-SPEED STEEL. 

Place of High-Speed Steel in Engineering. — When high-speed steels 
first came upon the market the reports of their marvelous powers were 
received with incredulous astonishment. To cut steel at the rate of a 
hundred, two hundred, and even four hundred or more feet a minute, 
almost as if it were cheese, seemed quite beyond the range of probabilities, 
not to say possibilities. Their actual performances, however, left no 
room for doubt that they would play an important part in the machine 
shop within the following few years, as indeed has now come to be the 
case to a much larger extent even than was at first anticipated. 

Extended Utility of the New Steels. — The first high-speed steels very 
naturally had defects which limited their usefulness as well as their use. 
It was seen very quickly that while it was possible to remove surprising 
quantities of metal, the tools could not be used for fine work, it being 
impossible to produce keen-cutting edges suited to finishing work on 
metal, or to wood-working and similar uses. From the fact that many 
who are familar with the new steels seem even yet to have the opinion 
that they can be used advantageously only for heavy metal cutting, it 
would appear that this characteristic still marks some of the steels on 
the market. However that may be, there has been such improvement 
of the quality, that is to say, of the structure, of high-speed steels through 
changes in their composition and the perfection and refinement of the 
methods of hardening and tempering, that there is scarcely a use to which 
a carbon steel tool can be put where one of high-speed steel will not only 
do more, but in most cases better work — provided, of course, the machine 
in which the tool is used is as well adapted. This may seem a trifle 
strong. There are manufacturers of high-speed steel, however, a number 
of them indeed, who unqualifiedly guarantee to make cutting tools to 
replace any carbon tool whatever with a high-speed tool, at a distinct 
saving to the user. However much their confidence may be justified, 
it has been demonstrated beyond question that high speed steel tools, 
despite the high cost of the material, compared with carbon steel, are 
more economical in four out of five jobs, generally speaking, in the 
metal-working industries, and in even a larger proportion of cases in 
certain other industries where cutting tools are required. 

186 



RANGE OF UTILITY OF HIGH-SPEED STEEL 



187 



Especial Field for High-Speed Steels. — Obviously alloy steel is peculiarly 
adapted to all operations where it is necessary to remove large quantities 
of superfluous metal, and to machine material so hard as to be quite 
beyond the power of ordinary tools, though it does not necessarily follow 




Fig. 152. 



The hew steels are especially effective in heavy cutting. Chips even larger than these are 
by no means rare in certain shops. M 



that in this sort of jobs it operates at its greatest efficiency, as may be 
seen hereafter. In some shops of course this sort of work is compar- 
atively large; but in the average shop such operations form but a small 
proportion of the work. The real test of the utility of the new tools is 
in their economical applicability to the multitude of ordinary jobs, for 
the doing of which ordinary tools have heretofore served very well. 

Limitations. — It must be quite evident that what has been said refers 
mainly to tools used for cutting. There are, however, a good many 
uses, as will be indicated hereafter, where high-speed steel is highly 
efficient in tools of a very different character. For the most part, 
however, it is applicable to cutting tools. It would be absurd, for exam- 



188 HIGH-SPEED STEEL 

pie, to make a sledge hammer of high-speed steel, at present cost, if 
intended for ordinary use. 

Conditions of Work Affect Efficiency. — It is important to bear in mind, 
when considering the relative efficiency of high-speed and carbon steel 
tools, the conditions under which they are worked. The latter have 
this advantage, under ordinary circumstances, of being used in machines 
designed with reference to their particular limitations and capabilities. 
The former, however, unless used in machines of the newer types, designed 
and built especially to withstand the tremendous strains and to give the 
extraordinary speeds and feeds applicable in the case of high-speed 
tools, cannot in the nature of the case work at their highest efficiency. 
The high-speed tool must be used in a high-speed machine, in order to 
develop its powers and show its relative value as a tool. Under such 
proper conditions, there can be no question whatever of the superiority 
of high-speed tools over ordinary ones, in all cutting operations at least. 

Pre-eminence in Heavy Cutting. — In the case of heavy cutting, the 
removal of large quantities of metal, of course the new tools are pre- 
eminent. But the question may well be asked, why should it be neces- 
sary to remove large quantities of metal, except possibly in a few cases 
where it is impossible to forge or cast nearly to the required shape? 
Well, it is cheaper to do it, in very many if not in all cases. Take, as an 
extreme example, the making of a very large crank shaft. It is scarcely 
within reason, under present conditions in shops capable of handling 
work of such magnitude as a hundred or a hundred and fifty ton forging, 
to work such a piece down under the press or hammer to the required 
dimensions and form. The forging concludes with a rough approxi- 
mation of the finished form and dimensions, and the machine tool does 
the rest. Even the tong-hold or porter bar is drilled off. 

For a long time it has been understood in well-regulated shops that 
when the amount of metal removed is not great, compared with the size 
of the piece, it is much cheaper to manufacture from bar stock pieces 
duplicated in large numbers, rather than first to forge them. Now that 
high-speed steel is available, it is demonstrated that the same thing is 
true where it would be necessary to remove a great deal of metal. A 
specimen job is shown in the annexed figure (154). The hatched portion 
shows the metal cut away from the bar stock. It is seen to be con- 
siderably greater than that remaining in the finished piece — two and 
a half times as great, indeed; for the weight of the part before finishing 
is a little greater than 117 pounds, while after finishing it is but 34£ 
pounds, the chips removed weighing a trifle over 82J pounds. Even 
with this great waste of material the cost of producing this particular 
piece has been considerably reduced by omitting the forging, and rapidly 
reducing from the bar with a powerful lathe. The milling operation at 
the end is of course the same as it was when made in the old way. 



RANGE OF UTILITY OF HIGH-SPEED STEEL 



189 




S.2 



190 



HIGH-SPEED STEEL 



Forging vs. Heavy Cutting. — In jobs such as constitute the ordinary 
run of work in factories, the design of parts naturally avoids, as far as 
possible, such forms as require a great deal of forging or cutting; and 



U-~2 i '--4 t — 3-^ — 4^-l-^+f — zyb*— & — 3^--4-i^ 




Fia. 154. Typical piece of work especially adapted to rapid reduction by use of multiple tools, rather than 
forging approximately to size and then finishing on lathe. 



cases like that just taken are comparatively rare. There is on this 
account usually a good margin between the cost of forging and finishing, 
and finishing directly from stock, in much of the work going through 
any particular shop. 

The Situation as it affects Castings. — In the case of iron and steel 
castings it is about as easy and cheap to mold close to the required size 
as not to do so; and ordinarily there is little, if anything, to be gained 
by heavy cutting, except in finishing the tops of large castings where 
defects not infrequently are of such a nature as to require the removal 
of considerable metal. In the case of small castings, or those of unusual 
form, which are peculiarly susceptible to warping, it is often desirable 
to mold large enough to allow for all possible deformation, and then 
to remove the excess of metal by machining. So also the drilling of 
holes, even large ones, often is more economical than coring and reaming 
them. 

The utility of high-speed tools on cast iron has been questioned, it 
having been widely asserted that the new steels would not work any 
better than carbon tools — if as well. Whatever foundation there may 
have been in past experiences to warrant such conclusions, there is no 
longer any ground for doubting the utility of high-speed steel for cutting 
cast or malleable iron. The former has been turned at a speed in excess 
of 200 feet per minute, and regularly for all-day runs at 130 to 140 feet. 
It is no extraordinary performance to take a ^\X^\ roughing cut on gray 
iron at 60 feet per minute, and a finishing cut ^ X T % at 100 feet per min- 
ute; though possibly this is not yet a regular thing in shops. High- 
speed steels of to-day cut cast iron as freely and smoothly as they do 
steel, though indeed the same speeds are not attainable. 

Basis of Tool Cost. — Even if there be no occasion for heavy cutting 
power, or for increased speed in light cutting or finishing jobs, there is 
a positive advantage in the use of high-speed tools for this purpose in 



RANGE OF UTILITY OF HIGH-SPEED STEEL 



191 







-a 

■- t-, 



01 fe 

0. OS 
«3j3 



«3 






c a; 

3 
Eh 



192 HIGH-SPEED STEEL 

that the cost of tool and tool maintenance is materially reduced. The 
first cost of a tool is usually held to be a matter of high importance; 
whereas it is, except only in the case of special tools when but a few 
pieces are to be produced, only one of several things to be considered, 
and not necessarily the most important of them. The only rational 
basis for computing the cost of a tool is the cost per piece of work sat- 
isfactorily finished. Obviously, then, the first cost may even become 
negligible. A much more important consideration than first cost is 
maintenance cost, which of course depends in large part upon the en- 
durance of the tool, which is to say its capacity for continuously doing 
work accurate within the required limits. The principal consideration 
affecting tool cost, then, is maintenance, first cost being quite secondary. 

Maintenance Cost. — To maintenance is properly chargeable the time 
required for removing the tool from the machine, putting it into con- 
dition suitable for proper work, grinding or dressing, the time lost by 
reason of the machine being idle, and again setting up in the machine. 
Evidently the longer a tool continues satisfactorily at work, the lower 
the maintenance cost, not only in the absolute, but relatively to the 
pieces finished; and consequently the greater the efficiency of the tool. 
Considered in this way, there will be found few cutting jobs in the ordi- 
nary metal-working shop in which high-speed tools cannot show a dis- 
tinct advantage. Let us see how this works out in specific instances. 

A Specific Case. — The following data could be duplicated many times 
in their essential features, in almost any shop, and are therefore typical: 

Pes. per Time for Total Pes. First Cost Cost of Time, 

Grinding-, etc. Grinding, etc. Finished of Tool per Hour 

Carbon 50 5 min. 1,000 $0.25 $0.20 

High-Speed 300 5 min. 10,000 .75 .20 

From these data the following comparisons are drawn per 100 pieces 
finished: 

m , t-i- a. ^ i. Cost of - , . _, , Saving, H.-S. 

Tool First Cost ,„ . . Total Cost J" , 

Maintenance over Carbon 

Carbon $0,025 $0,033 $0,058 

High-Speed .0075 .0055 .013 78% 

Putting the result in a different form, the first cost and maintenance 
of a high-speed tool on this particular (but typical) job is but little more 
than one-fifth that of a carbon steel tool — and this without any change 
whatever in speed or feed, the whole gain being in the greater endur- 
ance of the tool. With an increased speed or feed, or both,' of course the 
efficiency would have been still greater. 

Growing Use of Chilled Castings. — There is a growing disposition to 
make use of chilled rather than sand-molded castings for a variety of 
purposes. The difficulty of machining such castings has heretofore 
prevented the extension of their use except in rolls and wheels, and a 



RANGE OF UTILITY OF HIGH-SPEED STEEL 



193 



few other parts where their use could not well be avoided. Chilled 
rolls have indeed been turned with the very best of tools and at an 
extremely slow rate; but further than this little has been possible. 
With high-speed tools of proper form it is comparatively easy to rough 
down rolls and similar parts to cylindrical, and even to circular and 
spiral-grooved forms. For reasons not well understood, high-speed steel 
is apparently not so well suited to smooth finishing chilled surfaces, 
hadfield (manganese) tools being customarily used for scraping to 
secure the finish surface, unless this be done by grinding. The ordinary 
forms of tools are quite inadequate for the turning of chilled pieces, 
and it is necessary to use a special form of cutter. 




Fig. 156. 



The new tools have given a strong impetus to the use of the milling machine in places where 
previously the planer or shaper was considered necessary. 



In Reciprocating Machines. — The inherent weakness of reciprocating 
machine tools, the stopping at the end of each stroke and the return for 
another cut, for some time tended to prevent the use of high-speed tools 
in connection with them. There have been developments, however, 
which make their use in machines of this class almost if not quite as 



194 HIGH-SPEED STEEL 

desirable as in the case of rotating tools or work. Even if there were no 
advantage gained in speed or cut, the same reasons which make high- 
speed lathe tools desirable, even where increased speed is not desirable 
or attainable for any reason, apply to planer, shaper and slotter tools 
also, though possibly to a somewhat less extent. The time gained in 
grinding is somewhat less, though the real tool cost, measured as already 
described, is relatively the same. 

Speed Gains in New Types. — As a matter of fact, however, there is, 
in the newer machine tools of these types, a very considerable gain in 
speed, to say nothing of the possibility of increased cutting power. 
These machine tools, mostly of the recent rapid-stroke and quick-return 
design, require high-speed tools in order to work at their highest efficiency. 
A speed of 80 feet per minute has been attained effectively, while speeds 
of 40 to GO feet per minute on steel are no longer considered remarkable. 
It might be expected that the jar attendant upon the tool beginning a new 
cut after each return would very largely increase the wear of the machine. 
This might be true if the latter were lightly built; but in the case of 
properly designed and constructed machines the effect is unimportant. 
It is to be remembered in this connection that the power absorbed in 
high-speed cutting is by no means proportional to the increased amount 
of work done. There is more likelihood that the tool will snap off with 
the shock of the impact, though this cannot happen if it be of suitable 
proportions. 

An Example of Rapid Planing. — It is the regular thing in one shop 
to plane certain tough steel forgings under unusually difficult conditions 
at the rate of 40 feet per minute, cut \ X J inch, and to rough-plane cast- 
iron plates 12 X 23 inches in six minutes. The finish cut takes half as 
long. All this on a 36-inch planer. A 24-inch machine of the same 
design has been run at a speed which reduced the cost of the job on 
which it is regularly used from 30 to 8 cents per piece, at the same time 
increasing the former output of from 9 to 12 pieces to from 40 to 55 pieces. 
Such a quadrupled efficiency of course cannot be expected as a regular 
thing. 

The Case of Milling Cutters. — The evident tendency of the milling 
machine and rotary planer to supplant reciprocating machines has been 
accentuated by the new steels, whose efficiency is not subject to the 
same limitations in the form of a rotating tool as in the reciprocating 
form. All that has been said of other forms of high-speed tools with 
respect to their superior efficiency, holds true of milling and other rotary 
cutters, possibly to even a still greater extent. As with other tools, the 
lasting quality, the decreased amount of sharpening required, is an 
important item — more important even than in the case of lathe and 
similar tools, because of the higher cost of sharpening. The important 
gain, however, is usually in the greatly increased feed allowable with 



RANGE OF UTILITY OF HIGH-SPEED STEEL 



195 



high-speed cutters. An increase in speed also is permissible; and while 
advantage is often taken of this, the best practice in milling operations 
seems to be to increase feed rather than cutting speed. This on all 
classes of iron and steel. For this reason it is necessary, in designing 
these tools, to allow increased clearance to the cutting teeth and to 




Fig. 157. Rotary planer, which is taking the place of the reciprocating machine in many kinds of work. 
The gain from the use of high-speed cutters is much more pronounced than in the reciprocating type, 
whose speed is necessarily limited. 



reduce their number below that customary in carbon steel cutters of 
similar size. The design of these and other tools is considered else- 
where; so that it remains to point out here merely that usually, and 
especially in the case of those mills with narrow faces, inserted cutters 
allow the manufacture of a comparatively inexpensive tool in all diam- 
eters over say 4 inches. The body, once made, serves for an indefinite 
number of cutter sets. In smaller sizes than that mentioned it is usually 
desirable that the cutters be solid. 

Milling Cutter Efficiency. — A single typical case will indicate the 
efficiency of high-speed milling cutters compared with those of carbon 
steel. On cast iron a 3-£ inch cutter, 18 spiral teeth, cuts at a surface 
speed of 82 feet per minute with a table travel of 27 inches per minute, 
and mills 6800 linear inches at a grinding. The best results previously 
obtainable under similar conditions were 1300 inches to a grinding, at 



196 



HIGH-SPEED STEEL 



a table feed of only 15 inches per minute. The carbon tool required 
grinding once a day, whereas the high-speed cutter runs five times as 
long, finishing about 1360 pieces to the 270 pieces formerly finished per 
grinding. It was possible to reduce the labor cost from $1.40 to SI. 10 
per hundred pieces. Besides, there was the saving in the cost of grinding 
amounting to $0.11 per hundred pieces, making the entire saving $0.41 
per hundred pieces, or enough to pay for the first cost of the new tool 
in a week's time. In addition to this, the tool itself has an almost indefin- 
ite life, outlasting from five to twenty carbon steel tools; so that con- 
sidered merely with reference to the first cost and total amount of work 
done, the high-speed cutter is only one-fifth to one-twentieth as expensive 
as the other. 

Gear Cutters and Like Tools. — Accuracy of form and long life are 
especially desirable, and indeed essential, in involute or gear cutters 
and other formed cutters. The advantage of high-speed steel for tools 
of these types is so evident as scarcely to need mentioning. 




Fig. 158. Typical job of gang milling where high-speed steel tools pay. The finish on this job (cutters 4" 
and 8" diameter, 66 r.p.m., table traverse about If" per minute) is within the accuracy limit of 0.001", 
and no hand finishing is necessary in fitting pieces together. Courtesy Cincinnati Milling Machine 
Company. 

Milling Refractory Materials. — The efficiency of high-speed milling 
cutters when working on refractory material has been repeatedly ques- 
tioned. It is safe to say that any such question must be due to unfortu- 
nate and unnecessary experiences. Such milling cutters are successfully 
working on material as refractory as nickel-chrome steel armor plate, 
and that at a rate as high as 75 feet (peripheral) per minute. Working 



RANGE OF UTILITY OF HIGH-SPEED STEEL 197 

on automobile parts even more refractory, high-speed cutters are found 
to last three to five times as long as carbon steel cutters on the same 
work, and do it equally well, while the feed is increased a third or more. 
There is no difficulty whatever in the tools standing up under the work. 
It is merely a matter of correct design and proper hardening to meet the 
requirements of the case. 

As to Drills. — Next to lathe tools it is in drills that high-speed steel 
has most fully justified itself. In the up-to-date shop, drilling oper- 
ations have been as much changed as have the turning operations. 
Speeds, and more especially feeds, have been increased, heavier machines 
are required, and multiple work changed from punching to drilling where 
that has been possible. In putting holes through plates, especially 
plates where the distressing of the material involved in a punching 
operation is sought to be avoided, the drill is now taking the place of 
the punch. Such plates can be stacked and the holes drilled as quickly 
as they can be punched — and in some cases even more economically. 
The result is a better hole, if nothing else be gained. In agricultural 
and other machine castings, where it has been customary to core holes 
and then ream them out, it is now often less expensive to omit the 
cores and drill the holes from the solid. The result, generally speak- 
ing, is a more accurate hole, even when there is no direct economy in 
labor cost. * 

Efficiency of Small Drills. — It may be questioned if there be any 
considerable economy in the use of very small drills, say under { inch. 
There is not enough metal in sizes smaller than this to withstand the 
rough usage which may freely be given larger drills; and with speeds and 
feeds much increased there is likely to be considerable breakage. Never- 
theless there have been obtained some striking results with these small 
drills, and they are made for sale down to | inch and less. A \ inch 
drill has been run continuously in mild steel at the rate of about 1100 
revolutions per minute with a feed of .008 inch per revolution, without 
breaking down, and in grey iron somewhat faster. The rate agreed 
upon by common consent for carbon steel drills under similar conditions 
is about 220 revolutions per minute with a feed of about .005 per revolu- 
tion. Stated in terms of peripheral speed the ratio is 826 to 176, or 
about 4.5 to 1. The same ratio can be maintained easily throughout 
the larger sizes also; and when it is remembered that the allowable feed 
is practically doubled,- it is seen that the amount of metal removed in a 
given time is in the ratio of nearly 10 to 1. This looks big, very big. 
The actual economy, however, is not necessarily in proportion to the rate 
with which metal is removed, for the labor cost, as indicated elsewhere, 
is dependent upon a number of other factors also — the time lost in 
handling the pieces and in keeping the tool and machines in a state of 
efficiency, chiefly. In operations involving the boring of many shallow 



198 



HIGH-SPEED STEEL 




Fig. 159. In multiple drilling, like that here illustrated, the breakage or dulling of one drill means the 
stoppage of the work of a large number of others. The need for long life per grinding and for free- 
dom from breakage ia obvious. 



RANGE OF UTILITY OF HIGH-SPEED STEEL 



199 




w?w, 



ww?mmm 



" n 



Twist 



Flat 



holes and many changes of pieces, therefore, — that is, where the actual 
working time of the drill is short, compared with the whole time devoted 
to the piece, — the chief gain is in the longer life of the tool and the time 
saved in keeping it sharp. 

Cause of Excessive Breakage of Drills. — The excessive breakage of 
high-speed drills sometimes occurring in working on structural forms, 
boiler plates, and similar high-carbon plate work, is not at all necessary. 
It occurs most frequently because the drills used are not adapted to the 
work in hand. Drills for this purpose should have a very tough temper 
and smooth finish, and usually are better if twisted from rolled stock 
rather than milled from the round. 
Another cause for such breakage 
is the insecure holding of the 
several parts or plates when holes 
are being drilled through several 
members at the same setting. 

Increasing Use of Flat Drills. — 
In passing it may be of interest 
to mention that in many kinds of 
work flat drills are just as efficient 
as the twist variety — in grey iron 
they are found frequently to be 
slightly more economical. In steel 
forgings the twist drills are con- 
siderably the more efficient, 
however, as may be seen from 
the accompanying figure (160). 
Straight-grooved drills made from 
round stock are also quite 
efficient, though not quite so 
cheap to manufacture as the flat style. Of course the efficient use of 
drills of these forms involves accurate and correct grinding, just as in 
the case of twist drills. 

The Case of Rose Reamers. — Multiple-lipped drills, rose reamers, and 
similar boring tools are in the same category with drills in respect to the 
economies to be effected and the manner of effecting them. One con- 
sideration, however, differentiates them to some extent. The latter 
types of tools, employed mainly in enlarging or truing holes already 
existing, take a relatively thin skin of metal only (usually more or less 
chilled and sand-covered), instead of a chip corresponding nearly to the 
semi-diameter of the tool, the metal all being removed by the peripheral 
part of the cutting edge only. The tendency, therefore, is to wear the 
outer angle of the tool and to reduce the size. This tendency is pro- 
gressively intensified when once the wear has begun, and necessitates 



Twist 



Fig. 160. 



Drilling. Total cost per 100 lbs. of metal 
removed per hour. 



200 



HIGH-SPEED STEEL 



careful watching in order that the grinding may be frequent enough to 
insure not only accuracy, but efficiency. The advantages of a tool that 
will hold an edge for a long time under such conditions is evident. The 
first cost, as in the case of milling cutters, need not necessarily, in the 
larger sizes, greatly exceed that of less efficient tools, since inserted 




Fig. 161. An unusual special machine for drilling a large number of holes simultaneously in pieces of a 
single kind. Machines of such highly specialized type are peculiarly adapted to high-speed tools. 



blades can be utilized almost, if not quite, as freely as with the milling 
tools. A reamer designed so as to permit the use of the body an indefinite 
number of times in connection with renewals of the blades, distributes 
the first cost in such a way that it becomes actually less, and usually 
much less, than that of ordinary tools. 

High-Speed Hand Tools. — In connection with drills and reamers one 
is reminded of the stock joke concerning the man who bought a high- 
speed bit for use in ratchet drilling and who was disappointed because it 
did not cut any faster than those which he had been accustomed to 
use. The joke has now quite lost its point, for the new steels are coming 
into larger and constantly increasing use in hand tools. The gain of 
course is not in greater cutting speed, but in the longer life of the tools 



RANGE OF UTILITY OF HIGH-SPEED STEEL 201 

and the greatly lengthened time during which they can be used without 
re-grinding. A flat drill, for example, has drilled, as a regular thing, some 
1500 one-inch holes per grinding in the webs of 80-pound rails, as against 
about 50 holes drilled by a carbon steel drill — a gain in efficiency which 
practically eliminates the cost of grinding in this case. In other instances 
that could be cited the gain has been twice, and even three times, as 
large. 

Hand Files and Hand Reamers. — The high-speed steel hand file also 
seems an anomaly. It is, however, an actuality, and seems to justify 
itself in that it lasts some four or five times as long on steel and iron as 
an ordinary one will, and after that is still suitable to use on brass and 
other soft metals. Such files rarely break; and this is no small additional 
advantage. 

In hand reamers and the like tools there is an advantage greater still; 
for these are customarily used for accurate sizing, and their life is limited 
to the time during which they retain their size within the required limits 
of accuracy. Even when made capable of slight expansibility, the life 
of a carbon reamer of this class is short enough. The question may 
well be asked, in view of the very great superiority of the reamer made 
of high-speed steel, what profits it to use the former at half the cost 
when the life of the latter is ten to twenty times as long? 

Considerations Affecting Threading Tools. — The same considerations 
which affect small drills likewise affect small threading dies, taps, and 
similar tools. If left hard enough for the most rapid cutting, the small 
cutting points or edges are too brittle to stand up to the work. Proper 
hardening (say by the barium process) and tempering, however, entirely 
obviate this difficulty if the design is at the same time slightly modified, 
as pointed out elsewhere. The cutting speed is of course less than 
would be possible if the highest heats could be used in hardening. Taps 
as small as j\ inch have been used under these conditions at an efficiency 
ten to fifteen times that obtainable from carbon tools. In automatic 
machines the time lost in replacing dulled cutters is one of the important 
items which can be materially reduced by the use of the new steels. 
The breakage of taps is even less than with the old tools, if they have been 
properly treated. 

It does not seem necessary to .consider at length other varieties of 
cutting tools comparable to those already mentioned, except perhaps 
cutting-off saws and the like. The former, in action and efficiency, 
are affected by about the same considerations as those previously con- 
sidered. 

Sawing Operations. — Between the hack-saw blade of old, and the best 
cutting-off saw made prior to the application of high-speed steel to 
such use, there is a difference, to be sure. But all tools of this class 
have been lamentably inefficient. The high-speed steel hack-saw blade, 



202 



HIGH-SPEED STEEL 



now considerably used, of course much outlasts the ordinary sorts in 
both hand and power sawing. The latter mode of cutting, however, is 
itself very inefficient and is properly being displaced by high-speed band 
and circular saws. The band saw, until recently thought impracticable, 
if indeed not impossible, is undoubtedly the most efficient for sawing 
high-speed steel itself, and likewise is highly efficient for sawing all other 




Fig. 162. High-speed cold saws are used not only for cutting structural and other forms, but for slotting 
operations. These saws are also suited for hot sawing. 



kinds of iron and steel structures and forms where the nature of the case 
permits its use — as often it does not. In those cases the circular 
saw comes into play with a high efficiency. This of course does not 
cut metal as if it were wood, but certainly at a rate somewhat in keeping 
with present ideas of expedition. 

Inserted Tooth Saws. — Narrow-faced milling cutters have heretofore 
been used, for the most part, in high-speed sawing. It is now possible, 
however, to obtain saw plates of a considerable diameter. Such plates, 
in sizes above, say nine 'or ten inches, have been rather difficult to make; 
and even now it is doubtful if it is desirable to use them, except possibly 
in special cases. The inserted cutter idea is peculiarly applicable to 
circular saws of large diameter; and such tools are now considerably 
used, not only for cutting off, but for slotting and similar work. A 
special type of machine is required for such work, especially if heavy. 
A number of these are now available and give promise of taking an 
important place in the metal-working industries. A typical case is that 
of a recent machine operating two saws of 73 inches diameter, cutting 
1 T % inch slots. Such an operation would be quite out of the question 
but for the new steels and the inserted cutter. 



RANGE OF UTILITY OF HIGH-SPEED STEEL 



203 



In Non-Cutting Operations. — There is a constantly increasing use of 
high-speed steels for purposes which do not involve cutting, in the ordi- 
nary sense, at any rate; and in which increased speed is not the end 
sought any more than in the case of hand tools. Among these uses are 
those involving the shearing of metals, including among other tools 
shear blades, punches and broaches, blanking dies, and cutting-off dies. 
The economy in all these cases obviously is entirely in the longer life and 




Fig. 163. Tindel inserted-tooth cold saw. 

the reduced number of grindings necessary. Unless small, shear blades 
and cutting-off dies rarely are made of the solid high-speed steel stock. 
Usually the custom has been to bolt a relatively thin plate to a support- 
ing block; or in the case of heavy work, brazing the high-speed face to 
the backing. The recently developed methods of electric and autoge- 
nous welding makes it possible to get practically solid tools at small 
expense for alloy steel. 

Efficiency in Blanking Dies. — Blanking dies, if small, usually are of 
solid high-speed steel; though there is no objection to making them with 
a cheaper backing. Larger dies, of course, always have the face only of 



204 



HIGH-SPEED STEEL 



high-speed steel. The cost of such a compound tool need not be greater, 
usually, than that of the ordinary kind; and frequently it may be less. 
The question in tools of this sort is that of getting and maintaining a 
sharp, clean shearing edge. Otherwise the work is likely to be indiffer- 
ently done. Once the edge has begun to upset or wear away, the tendency 
is toward a progressive deterioration until it is necessary to re-face by 
grinding. The superiority of high-speed steel in this kind of work is 
sufficiently indicated by one example. In blanking sections for agri- 
cultural machine knives, 14,000 to 15,000 pieces per grinding is con- 




Fig. 164. High speed is especially efficient in blanking dies. A pair of dies like this has blanked a 

million pieces. 



sidered average work for a good die of special die steel, while the total 
output might reach 150,000 to 160,000 pieces. A high-speed die on the 
same work (blanking from 11 to 16-gage polished bands of medium- 
carbon knife steel) produces regularly 40,000 to 50,000 pieces per grind- 
ing, and the average total output is about 1,000,000 pieces — the maxi- 
mum record for such a die being about 2,600,000 pieces. The saving in 
grinding, therefore, is two out of every three; and the life of the die aver- 
ages that of some twenty of the special steel dies. A little figuring as to 
the cost of each kind makes a very interesting study under these con- 
ditions. Of course the relative efficiency of such dies will vary a good 
deal according to the material and the working conditions; but a sub- 
stantial increase in efficiency in practically all cases is certain. 

In Punching Operations. — In punching operations, properly so called, 
the same high efficiency may be expected — indeed considerably higher, 
usually. The ordinary punch generally gives out by collapsing or break- 
ing off after the edge has become somewhat dulled. The increasing 
force required to drive the tool through, that is, to shear off the metal 
removed to form the hole, seems to increase very rapidly the molecular 
fatigue or intensifies already existing internal strains to such an extent 
that the endurance limit is soon reached. In punches made of high- 
speed steel the shearing edge wears much less rapidly, and, if suitably 
hardened and tempered, the body longer resists the strains than in the 



RANGE OF UTILITY OF HIGH-SPEED STEEL 



205 



case of ordinary tools, as is indicated by the typical performance of a 
I inch punch working in medium carbon channel iron § inch thick. 
The average life is between 50,000 and 60,000 holes, whereas that of a 
tool steel punch rarely reaches more than 6000 holes. This ratio is 




Fig. 165. 



Gang punch, where the breakage (oftenest because of first becoming peened over) of one punch 
means considerable delay. 



found to be quite common. In broaching operations, such as are usual 
in connection with malleable castings, the efficiency is, if anything, 
rather greater. 

Objections to High-Speed Punches, Taps, etc. — The objection is often 
made to high-speed punches, as to taps and small drills, that they are 
too brittle. The same answer, however, applies, namely, that proper 
hardening and annealing, to give requisite toughness (always assuming 
a properly selected brand of high-speed steel, for these differ a good 
deal in this respect among themselves), obviates the danger of breakage, 
or reduces it to a minimum. Small sizes of punches, when for use in 
punching thick and high-carbon steel, are indeed rather difficult to harden 
and temper to just the point where the combination of hardness and 
toughness is right for maximum performance; and unless this problem 
has been well worked out in connection with the particular material 
worked upon, the increase in efficiency will be slight, if indeed there be 
any at all. In hot punching the gain is considerably greater than in 



206 HIGH-SPEED STEEL 

cold, since the temper is not drawn by the hot material, as is likely to 
be the case with ordinary punches. For the same reason dies of these 
new steels are especially efficient in hot cutting-ofT and similar hot work. 

Forming Dies and the Like Tools. — Since the advent of the readily 
worked low carbon sheet steels, working freely in press dies, the dis- 
placement of small castings by formed steel pieces has been going on 
apace, and the press-working of sheet metals has come to be an important 
branch of metal working. In all but the simplest of forming dies the 
wear on certain parts is excessive, compared with that on others; and in 
consequence the dies, usually expensive on account of the very narrow 
limits permissible in respect to their accuracy, soon become worthless 
because they have become worn beyond the limits allowable for good 
work. Even the hardest carbon steel forming dies have a compara- 
tively short life. This is especially true of embossing dies of intricate 
design. Since the principal item of expense in these tools, and partic- 
ularly in embossing dies, is in the highly skilled labor going into them, 
the first cost of the material is of little consequence. Anyway a part of 
the additional cost of the high-speed steel material can be saved by 
merely facing the dies with it, or making inlays at those places where 
the wear is greatest. In this case greater care in hardening is necessary. 

Place in the Forge Shop. — In the forge shop also the new steels are com- 
ing to claim an important place. Much that has been said of forming 
and embossing dies applies to drop and hot-press dies also. It is cheaper, 
that is to say, to use the more expensive material in the first place than 
to pay for the more frequent renewals necessary if ordinary steel is used. 
Whether because of some difficulty in hardening to a sufficient depth, 
or because of the drawing of the temper by the hot work, or for some 
other reason unexplained, drop and similar dies subjected to concussion 
frequently sink under the severe pounding which they receive, accentu- 
ating the effects of wear. High-speed steel dies do not seem to be 
subject to this failing. In the heading machine, and other hot-pressing 
operations also, high-speed steel dies show a relatively long life. The 
excessive wear and the liability to drawing the temper when made of 
ordinary steels and thus still further reducing the effective life, suggest 
the advisability of discontinuing entirely the use of carbon steel for such 
purposes and the substitution of some form of the new alloy steel, whether 
properly designated high-speed or not. The possible exception is the 
case of those dies subjected to such tremendous pressures, as in cold- 
heading very tough stock, that the die blocks often split. Wherever it 
is a matter of resisting wear and maintaining size, the new steel clearly 
has shown its title to preference. 

Drawing Dies and Miscellaneous Tools. — In no case has this been more 
notable than in such operations as wire drawing, and also in cold draw- 
ing. One of the chief difficulties always is the maintenance of a uniform 



RANGE OF UTILITY OF HIGH-SPEED STEEL 207 

size in the rod or wire passing through the die. If the material is excep- 
tionally hard and accurate sizing is essential, the difficulty is serious. 
An alloy steel die often outlasts thirty or more ordinary ones. A sim- 
ilar efficiency is frequently found in snap dies used for riveting of all 
sorts, especially in pneumatic rapid blow tools. Chisels used in the 
same kind of tools, and those used in file-cutting, also have a high effi- 
ciency, in spite of the often repeated assertion that high-speed steels are 




Fig. 166. Die for drawing down lead covering over table. 

not suited to tools of this sort and to any operations involving continued 
concussions. It is possible that their efficiency is not so marked in these 
cases; and undoubtedly in certain conditions there is likely to be small 
or no gain in their use. Nevertheless high-speed chisels and hammers 
are in successful and efficient service in such difficult work as riveting 
and trimming boiler plates, and chipping and hammering castings. 
Even a hand hammer of high-speed steel has been used to advantage in 
the latter kind of work. The efficiency depends a great deal upon the 
particular work required. Unquestionably the main reason why many 
tools for similar purposes have not been made of the new steels, to any 
considerable extent, has been the high cost of material. This reason no 
longer holds, since it is feasible to provide almost all sorts of tools with 
high speed steel wearing surfaces or cutting edges at small expense. 

Limitations of High-Speed Tools.-^If, then, high-speed steel has been 
found well suited to all these uses (as indeed it has, and to many others 
also), what are its limitations? Can all tools be profitably made of the 
new steels? By no means — yet, anyway. But in the machine and 
related shops, working in iron and steel, it seems probable that it might 
be so. It is certain that the men who have given the matter the most 
careful attention very generally are of opinion that there are compara- 
tively few uses in such shops where high-speed steel is not practicable 
and economical, though possibly few would care to go to the extent 
proposed by the superintendent of motive power of one of the largest 
American railways, who proposed to scrap the entire outfit of old tools 
and replace them with suitably and economically designed high-speed 
tools for finishing jobs as well as for ordinary work. 



208 



HIGH-SPEED STEEL 



About Finishing Cuts. — Whatever may have been the case with the 
early kinds, the assertions yet often heard to the effect that high-speed 
steel is unsuited to finishing cuts are mostly twaddle, based on insuffi- 
cient experience and upon experience with improperly designed or 
treated tools, or tools used in machines unsuited to the work in hand. 
Elaborate theories have been advanced to account for the lack of finish- 
ing quality in these steels — which lack does not exist, in good grades 




Fig. 167. Slitting knives for sheet metal cutting. 

at any rate, if in any. It is no uncommon experience to take finishing 
cuts (one cut only) from the bar at a high speed and leave a surface in 
every wise satisfactory and with an accuracy within 0.002 of an inch. 
In some shops finishing cuts are taken at a speed as high as 200 feet per 
minute, the feed being rather fine; and 30 to 50 feet is common practice. 
The tools and the machines, however, are properly designed and adapted 
to each other, and the former are hardened and tempered appropriately 
to finishing work. Milling cutters are very widely used for the finest 
kind of surfacing; and that at considerably increased speeds or feeds — 
generally the former where especially good surfaces are required. 

And High-Speed Shaving Too! — The ability to hold a keen edge, such 
as is presupposed where finishing cuts are concerned, has been facetiously 
referred to in connection with high speed steel razors, wherewith the 
busy man might indulge in high-speed shaving — the hope being also 
facetiously expressed that in this case the depth of cut be not unduly 
increased. Whatever may be the humor in such a situation, it is said 
to be a fact that certain "safety" razor blades of exceptional edge- 
keeping quality are made of high-speed steel. Occasionally also one 



RANGE OF UTILITY OF HIGH-SPEED STEEL 209 

comes across a knife, or other cutting tool, not intended for use upon 
metal, of the same material. One of the severest tests of keen edge- 
holding quality is paper cutting; and high-speed knives in paper-cutting 
machines are not to be compared with carbon steel knives in this respect. 
The same thing is true of other kinds of work that could be mentioned — 
in wood-working especially. 

In Non-Metal Industries. — Attention has been so concentrated upon 
the use of high-speed steel in metal-cutting operations that its utility 
in other and perhaps unrelated industries has been all but overlooked. 
Now that it has been demonstrated beyond question that high-speed 
cutters are highly efficient in wood-working and other besides the metal 
industries, it seems very probable that, as the writer predicted some 
years ago, there will shortly be as great a revolution in these as in metal- 
cutting industries. First used for wood-planer knives, high-speed steel 
is already largely employed for almost all sorts of wood- working cutters; 
and there is every reason why it should be used still more largely. 

Efficiency in Planing and Forming. — The cutting speeds obtainable 
with the old tools, applied to wood-cutting, have seemed already toler- 
ably good. With the new steels, however, the feed (the reference now 
is to surface and form cutting) can easily be doubled and a much better 




Fig. 168. Back knife for woodwork. Back made of soft steel, High-speed steel blade riveted on. 

finish obtained at the same time. Sixty feet a minute, as wood workers 
know, is considered a very high feed in planing and the like operations, 
and half as much is more nearly the average in most shops. With high- 
speed cutters a feed of a hundred and more feet is entirely practicable, 
regardless of the kind of wood — hard or soft, it is a matter of indifference 
to the knives. And the finish obtained has very little resemblance to that 
succession of ridges and depressions, the knife marks to which we have 
been so long accustomed. It is, on the other hand, smooth and satiny, 
more nearly comparable to the surface left by the sander or the hand 



210 



HIGH-SPEED STEEL 



plane. Forming cutter heads show the same characteristics of smooth 
finish and possible increased feed. 

A Case in Point. — The knives are able to cut faster because they 
retain a keen edge better and longer, and can actually be given sharper 
cutting edges than is permitted to carbon cutters, in which latter a very 
keen edge cannot be expected to stand up to the work for a satisfactory 
length of time. The edges, in all kinds of wood cutting, hold up re- 
markably, as may be seen from a typical instance. In a certain job of 
cutting dowels from very hard maple sticks, an ordinary cutter could 
not be made to work longer than half an hour without re-honing. Even 
then it was necessary to set up the knife several times in order to get 
the dowels properly sized. A high speed steel cutter easily runs thirty 




Fig. 169. High-speed hollow mills showing a high efficiency. 



hours without sharpening, and at the end of that time is in excellent 
condition, apparently able to run considerably longer without any need 
for setting up. This is an efficiency of over sixty to one in the matter 
of sharpening alone, saying nothing at all of a possible increased rate 
of cutting. In most wood-working jobs, sawing among the rest, the 
tools easily keep their edges from three to ten or fifteen times as long as 
the ordinary ones. The saving of time under these conditions is very 
evident. It is the more marked also since the tools can be readily 
designed so as to permit sharpening without removing the cutting blades 
(in tools of this type) from the heads or revolving holders. 

It scarcely need be added that the cutters, as far as practicable, are 



RANGE OF UTILITY OF HIGH-SPEED STEEL 211 

most economically made composite, that is, in the form of holders of 
iron or ordinary steel provided with thin cutting blades suitably clamped 
in place. 

Cutting Soft Metals. — The question has often been raised concerning 
the economy of high-speed steel in cutting brass and metals other than 
iron and steel; and most usually it has been said that there is little if 
any advantage. This is by no means the universal experience, for in 
certain shops they are used with a distinct saving on brass cutting; 
while in working other metals, as bronze and German silver, the saving 
in grinding is very marked indeed. An experience in milling German 
silver pieces is indicative of the many others. A high-speed cutter is 
in better condition after milling 5000 of a certain piece than is a carbon 
cutter after milling only 100 of the same piece. 

Tools Subjected to Abrasion. — Though apparently but little used for 
such purposes, outside of the metal-forming and shearing jobs, as already 
indicated, the new steels have been found efficient in a great variety of 
other operations involving heavy wear or abrasion. Among these are 
the drilling and surfacing of rock, marble and building stone generally. 

Not All Steels Widely Adaptable. — In conclusion it should be pointed 
out that there are high-speed steels, and still yet high-speed steels. And 
while it is quite true that such steel is available and efficient in all the 
processes just indicated, and in many others as well, it does not neces- 
sarily follow that any one brand is adapted to all these several uses. 
Indeed, most of them are not, though a very few seem to be of a com- 
position which adapts them surprisingly well to a very great range of 
work. Others are more particularly adapted to certain kinds of opera- 
tions; and still others seem to be altogether inferior. 



CHAPTER XV. 

CONDITIONS OF MAXIMUM EFFECT. 

Bringing Together Tool and Work. — Besides the two things ordinarily 
considered in bringing together a tool and a piece of work, namely the 
nature of the tool, and the form of the machine adapted to its most 
efficient application to the work to be done, there is a third consideration 
fully as important as these, and not at all rarely more so; and that is the 
proper bringing together of the tool and the piece to be worked. The 
form and type of machine by which such a relation is established of 
course is determined largely by the form of the tool selected and the 
nature of the work to be done; and in respect of this it is necessary to 
say little here, though it may be pointed out that the new steels have 
emphasized very strongly the tendency away from reciprocating machine 
tools and toward those in which either tool or work rotates. 

Effect of Multiplex Adjustments. — Until lately (and apparently yet, 
to a considerable extent) the primary end in machine design has been 
to secure facility; and to satisfy this requirement, movements and 
adjustments have been multiplied in standard machines until the tool- 
holding and applying mechanisms have not infrequently been made 
more mobile than rigid. The need for rigidity in the tool and work 
relation has been well enough recognized, though possibly lost sight of 
at times. In the new conditions imposed by high-speed tools rigidity 
and solidity are imperative. They are conditions without which there 
can be no such thing as efficiency. Hence it is of first importance that 
tool and work be brought together with the least possible intervention 
of parts and joints, and at as short a distance from the bed or frame of 
the machine as may be. Fortunately, as elsewhere shown, the large 
use of jigs and fixtures, in general manufacturing at any rate, makes a 
great variety of adjustments superfluous, and it becomes possible to 
have tool-holding and work-holding devices simple and rigid. 

Chatter. — Such a requirement is necessitated not only in order to insure 
a finish of the specified excellence, but from considerations affecting the 
life of the tool as well. At the very best the tool and its supports, to- 
gether with the other parts intervening between work and tool, and 
serving to hold them in proper relation, are in the nature of a spring 
under tension while cutting is taking place. This being so, it follows 
that with every variation in the pressure upon the tool end of the spring 
there is a corresponding variation in the tension, and consequently there 

212 



CONDITIONS OF MAXIMUM EFFECT 



213 



is a tendency toward vibration. The phenomenon of chattering, as 
seen in machine tools too light for the work to be done or too much 
worn to insure smooth running, is well enough known. But it is not so 
well known that under the very best conditions more or less vibration 
still is present, even in such tools as drills, reamers, milling cutters, and 





Fig. 170. 



Roughing cut, locomotive tire turning. The conditions were excellent, 
but vibration ia clearly evident. 



the rest. The usual opinion is that there is no quivering if no chatter- 
ing is heard and no vibration felt. The investigations of Dr. Nicholson 
have proved not only that pressure oscillations are always present, but 
that there is a definite relation between them and the character of the 
chip removed. A little study of the nature of chips, and the sur- 



214 



HIGH-SPEED STEEL 



face left by a tool, especially when very heavy cuts have been taken, 
shows the same thing conclusively. This is clearly shown in the accom- 
panying illustrations of locomotive tire turning, Figs. 170, 171 and 172, 
one showing a roughing cut, a second a finishing cut, and a third the 
chips roughed off. In the doing of this work the conditions were made 
as nearly perfect as possible, and the lathe used was of a type and build 
to prevent doubt as to its rigidity. 




Fig. 171. Tread of locomotive tire after finishing. 
Note corrugations indicating vibration of tool. 



Lateral Vibrations. — It is seen that corrugations left by the tool, Fig. 
170, and serrations or waves found upon the top of the chip, Fig. 172, 
have a rather regular recurrence and form. The same thing may be 
observed in other illustrations showing chips, whether the latter be large 
or small. It is apparent also that vibrations take place laterally as well 
as perpendicularly to the lip of the tool; and the Nicholson experiments, 
already referred to, have shown that the wave-like variations in pressure 
at right angles to the finished face correspond very closely with those 
resulting from the thrust away from the face and therefore perpendicular 
to it. Not that these two (and more than likely also quiverings in other 
directions, especially in the line of the feed or traverse) are distinctly 



CONDITIONS OF MAXIMUM EFFECT 



215 



separate. They are, as may be seen in the illustrations already referred 
to, combined into one resultant, which gives to the cutting edge of the 
tool a movement approximating the arc of a circle. 

Minimizing Vibration. — The importance, in respect of the finished 
work, of reducing this vibration to the lowest terms is obvious. It is 
no less important to the life of the tool itself, for it is this to a very large 
extent which destroys the cutting edge, and necessitates more or less 
frequent grindings according as conditions are more or less excellent. 
Under ideal conditions the tool would practically sharpen itself, while 
working, and its cutting life would accordingly be greatly prolonged. 




Fig. 172. Chips taken in turning locomotive tires, with conditions as well arranged as possible. 



Inasmuch as this prolongation of the life (that is, the lengthening of the 
time during which a tool will do its maximum amount of work without 
necessitating re-grinding) is one of the most important factors in the 
use of high-speed tools in general manufacturing, it is necessary to 
work the tool under those conditions which are most favorable to the 
accomplishment of that object in the highest degree. A brief inquiry 
into the nature of the cutting operation, therefore, is in order. 

Action of Ordinary Cutting Tools. — A wood-cutting tool works with a 
sort of splitting action. The sharp edge is forced across or through the 
material, which is then pushed apart by the faces of the thin wedge behind 



216 



HIGH-SPEED STEEL 



the cutting edge. The fibers thus are separated and a crack is opened 
which tends to precede the edge of the tool a greater or less distance 
according to the sharpness or bluntness of the cutting angle and the 
tenacity or brittleness of the material being cut. As the tool advances, 
the tendency is for the shaving to break, split, or shear as it is bent 
farther and farther from the straight, until perhaps it quite separates 
from the preceding portions. In cutting across the grain of wood, say, 
this is seen very clearly. Now in the case of the Hartness " sharp edge " 
tools and method of metal cutting the action seems to be very similar. 
The essential difference lies in the absence of fiber in the material cut, 
so that there is a sort of shearing of the chip as the cutting progresses, 




Fig. 173. How a wood-cutting tool acts. 



instead of a splitting apart of the fibers. Since all the flanks of such a 
tool ride against or are pressed upon by either the chip or the stock left, 
and the tool itself is free to move within a slight range, the cutting 
edge tends to sharpen itself and there is very little tendency for it to be 
broken off or to crumble away by any lateral movement, as is the case 
with tools of the ordinary form. 

Theory of Metal Cutting. — The action of a cutting tool as customarily 
designed and used, though in some respects similar to that described, 
yet differs in important respects. While the cutting part of such a tool 
is in the form of a wedge, and acts a good deal like one in first entering 
the metal, after the chip is once fully started the action is rather that of 
tearing away the chip from the mass of metal and scraping the rough 
surface left by the chip, the chip being the while broken or sheared into 



CONDITIONS OF MAXIMUM EFFECT 



217 



smaller or larger sections, as the case may be. Certain observations and. 
conclusions with reference to these phenomena were published some 
time ago by the present author. Since that time Mr. Taylor has 
published 1 further and amplified observations which cover the ground 
so thoroughly that his words are here quoted at length, with some slight 
adaptation. 




Fig. 174. How a chip is taken and sheared into sections in cutting steel. 

" The enlarged view of chip, tool, and forging shown, Fig. 174, repre- 
sents with fair accuracy the relative proportions which the shaving cut 
from a forging of mild, steel (say 60,000 pounds tensile strength and 
33 per cent stretch) finally assumes with relation to the original thickness 
of the layer of metal which the tool is about to remove. It is of course 
impossible to determine accurately the extent to which various parts of 
the chip and forging close to the tool are under compression and tension, 
but in general the theory advanced is believed to be correct. 

1 "On the Art of Cutting Metals," by Mr. Fred W. Taylor; being his presidential 
address at the opening of the annual meeting of the American Society of Mechanical 
Engineers, December, 1906. Published by the Society. Practically all references 
and allusions to Mr. Taylor's work and conclusions are based upon this address. From 
it also are taken the illustrations to which references are made in the quotation, as 
well as a number of others. 



218 



HIGH-SPEED STEEL 



Distortion of Shaving. — " The thickness of the layer of metal to be 
removed is indicated, on the same enlarged scale as the rest of the figure 
by L, Fig. 174, between the dotted line and the full line representing 
the outside of the forging. It will be observed that the chip is in process 
of being torn apart and broken up into three sections, between which the 
shearing action or cleavage has progressed to a greater or less extent 
according to the distance from the cutting edge. It will be noticed that 
the width of the sections is at their bases about double the thickness of 
the original layer of metal removed, and that their upper portions are 
not enlarged to the same extent. These sections are about three times 
as high as the original layer. It should be clearly understood that the 
dimensions of the sections will vary according to the hardness of the 
metal being cut, and also to a certain extent with the angles of the cutting 




Fig. 175. How hard and soft chips bear upon the lip surface of tool. The soft chip covers a much larger 

area of the lip surface. 



tool. The harder the metal being cut, the less will each section of the 
chip be enlarged. In other words, if the same shaped tool be used in 
each case, the chip from soft metal comes off very much more distorted 
than that from the harder steel. This explains why the total pressure 
on the tool has but little relation to either the hardness of the metal 
being cut or the attainable cutting speed. 

Explanation of the Figure. — " The chip bears on the surface of the 
forging, say, from point H to points (Fig. 174), and through this distance 
is under constant compression from the lip surface of the tool. This com- 
pression is transmitted through each of the sections 1 and 2 of the chip, in 
the direction indicated by the arrows, to the upper portions of the sec- 
tions, which are still unbroken and which act like a lever attached to the 
upper part of section 1 to tear that section away from the body of the 
forging, as indicated at point IV The tearing away of section 1 is 
assisted also by the pressure of the tool upon its lower surface. After 



CONDITIONS OF MAXIMUM EFFECT 



219 



this tearing action has started, the further breaking of the chip into 
independent sections would seem to be that of simple shearing. It 
should be borne in mind that in shearing a thick piece of steel the whole 
piece is not shorn or cut apart at the same instant, but the line at which 
rupture or cleavage takes place progresses from one surface through 
the metal until within a short distance from the other surface, when the 
whole remaining section rather suddenly gives way. In shearing steel, 
the metal at the point of rupture is pulled apart under a tensile strain, 
although on each side of the shearing line it is under heavy compression. 




Fig. 176. Structure of wide and relatively thin chip. Cut from armor plate. 



Shearing Action. — " As each of the sections of the chip successively 
comes in contact with the lip of the tool, its lower surface is crushed and 
the metal flows out laterally until it becomes about twice its original 
thickness or width. As in all shearing, when the full capacity of the metal 
for flowing has been reached, it tears apart under tensile strain from the 
body of the adjoining metal of the forging. The compression on the chip 
from the tool continues, however, and the chip continues to flow and 
spread sideways at a part farther from the tool surface, say at the points 
marked F. In the same way shearing continually takes place along the 
left side of the portion of the chip which is flowing or spreading out side- 
wise. There is no question that shearing takes place constantly along 
the left-hand edges of two of the sections at the same time, and it is 



220 



HIGH-SPEED STEEL 



probable that this action occurs most of the time along three lines of 
cleavage. 

Maximum and Minimum Pressures. — " Dr. Nicholson's dynamometer 
experiments show that the pressure of the chip on the tool in cutting 
a chip of uniform section varies with wave-like regularity, and that the 
smallest pressure of the chip is not less than two-thirds of the greatest. 
From this it is evident that shearing must be taking place along at least 
two lines of cleavage at the same time; since if each of the sections into 
which the chip is divided were completely broken off before the tool began 
to break off the following section, there must be times when there would 
be almost no pressure on the tool. 




Figs. 177 and 178 



Illustration oi the shearing of a chip into sections. The series formation, indicating 
vibrations of long wave length, is well shown. 



Shearing of Chip at Three Points. — " It is at first difficult to see how it 
can be possible for the chip to be shearing at two or three places at the 
same time. It should be noted, however, that above the points T ly T 2 , 
and T 3 the metal of the chip is still a solid part of the forging, and moves 
down at the same speed as the forging, in a single mass or body, toward 
the lip surface of the tool, and with sufficient force to cause each of the 
three sections of the chip to flow or spread out at the parts indicated 
by the three letters F. According to the laws governing shearing, rupture 
or cleavage in each case must take place as soon as the maximum possi- 
bility for flowing has been reached, and in each case shearing must occur 
at the left of the zone where the metal is flowing. It is probable that 
after the shearing action has progressed in section 3 to about the point 



CONDITIONS OF MAXIMUM EFFECT 



121 



indicated by T 3 , the whole of this section gives way or shears with a 
rather sudden yielding of the metal from T z to the upper surface of the 
chip. It is this rather sudden shearing which undoubtedly causes the 
wave-like diminution in the pressure of the chip indicated in Dr. Nichol- 
son's experiments. 




DIRECTION OF FEED 



Fig. 179. How the chip is removed — milling. Cutting edge of blade not under heavy pressure. 
Courtesy of Tabor Manufacturing Company. 



., . 



""•••iiimiMWlBpSif 



XjjiixrfSi 



Fig. 180. Chips milled from a steel forging. Courtesy of Tabor Manufacturing Company. 



Chip Torn from Body of Work. — " It would appear that the chip is 
torn off from the forging at a point appreciably above the cutting edge 
of the tool, and that this tearing action leaves the forging in all cases 
more or less jagged or irregular at the exact spot where the chip is 
pulled away, as shown to the left of 7\. An instant later the line of the 
cutting edge, or more correctly speaking, the portion of the lip surface 
immediately adjoining the cutting edge, comes in contact with these 
slight irregularities and shears off the lumps so as to leave the receding 
flank of the forging comparatively smooth. Thus in this tearing action, 
particularly in the case of cutting a thick shaving, while the cutting edge 
of the tool is continually in action, scraping or shearing off or rubbing 



222 HIGH-SPEED STEEL 

away these small irregularities left on the forging, yet that portion of 
the lip surface close to the cutting edge constantly receives much less 
pressure from the chip than the same surface receives at a slight distance 
beyond. This allows the tool to run at a higher cutting speed than would 
be possible if the cutting edge received the same pressure as does the 
lip surface close to it. 




Fig. 181. Some "sawdust" and a sawed surface. 

Evidences of Tearing Action. — "There are many phenomena which 
indicate this tearing action of the tool. For example, it is an everyday 
occurrence to see cutting tools which have been running close to their 
maximum speeds and which have been cutting for a considerable length 
of time, guttered at a little distance back from the cutting edge, Fig. 
182. The wear in this spot indicates that the pressure of the chip has 
been most severe at a little distance back from the edge. 

" Still another manner in which the tearing action of the tool is in- 
dicated is the case where a small mass of metal is found stuck fast to 
the lip surface of the tool, Fig. 183, after it has completed its work and 
been removed from the lathe. When broken off, however, and care- 
fully examined, this mass is found to consist of a great number of small 
particles which have been cut or scraped off the forging as above de- 
scribed, by the cutting edge of the tool. They have been pressed down 
into a dense pile of compacted particles of metal stuck together and to 
the lip surface of the tool, almost as if welded. In the case of modern 
high-speed tools, when this little mass of particles is removed, the cut- 



CONDITIONS OF MAXIMUM EFFECT 



223 



ting edge of the tool is in most cases found about as sharp as ever 
and the adjacent lip surface not infrequently shows the scratches left 
by the emery wheel from the original grinding." 





Fig, 182. Cutting edge still good but deep groove worn 
or guttered in the lip surface by the pressure of the 
chip. 



Fig. 183. Small particles of the chips 
scraped from the forging and pressed 
into a compact pile upon the lip sur- 
face of the tool. 



Difficulty of Machining Cast Iron. — This peculiarity in metal cutting 
seems to explain why it is not possible to machine cast iron and other 
brittle materials as rapidly as steel and other tenacious substances. 
In the latter case the chip is split off from the main body with a line of 
cleavage extending some distance ahead of the cutting edge, and tending 
more or less to follow the direction of the cut; whereas in the former 
case the brittleness of the material tends to prevent the line of cleavage 
advancing much, if any, beyond the cutting edge, while at the same time 
its direction tends immediately toward the surface of the chip rather 
than in the direction of the cut. In consequence the edge of the tool 
has a great deal more work to do, scraping or shearing off the relatively 



224 HIGH-SPEED STEEL 

much greater amount of material left behind by the chip in breaking 
off from the main mass. The tendency, therefore, is for the edge to wear 
away rapidly. 



Fig. 184. Typical chips made in cutting cast iron. 

Wear of Tool in Steel Turning. — In the case of steel cutting, say, the 
major part of the work falls upon the well-supported lip surface back 
of the edge, the distance depending upon the nature of the material 
and the feed or depth of cut. The rubbing of the chip tends gradually 
to wear a depression or pit into the lip surface, the form and place vary- 
ing according, among other things, to the nature of the material being 
cut and the rake of the tool. If the cutting speed and its concomitants 
are such as to generate a great deal of heat which cannot be conducted 




The Engineering Magazine 

Fig. 185. The line ab indicates the rake or slant which in this particular case would allow the tool to 
work at its greatest efficiency, for it is the slant established by the abrasive action of the chip itself. 
The dotted line indicates what would be the ideal tool in this case but for other considerations. 

away rapidly enough to keep the tool below the temperature where 
softening takes place, the lip surface quickly wears away along with the 
softened cutting edge. When, however, the temperature of the cutting 
edge and the adjacent parts is kept below the softening point, the abra- 
sion of the lip surface takes place gradually and rather uniformly, the 
tendency being to form a hollow whose front surface forms a sharper 
angle with the clearance flank of the tool, and therefore gives a sharper 
cutting angle to the tool as it approaches the edge. As this angle be- 
comes still smaller the cutting edge has less and less support, and tends 



CONDITIONS OF MAXIMUM EFFECT 



225 



to wear more and more rapidly, or to crumble away under lateral vibra- 
tion. This latter, together with the quivering in the line of the cut 





Fia. 186. Tool run at such high speed as to 
be ruined while cutting. 



Fig. 187. Wear on tool run at proper speed. Tool 
still in good condition. 



already referred to, subjects the cutting edge to a succession of blows, 
which tend to break it over some- 
what as is the case when a piece cf 
wood is scraped with the edge of a 
freshly broken glass. Immediately 
the edge becomes nicked, be it ever 
so slightly, the whole of it very 
rapidly goes down, generally by reason 
of the increased heating attendant 
upon the rubbing of the damaged 
part against the work, instead of shearing away the material as 
before. 




Fig. 188. Spalling of 
tool point by down- 
ward pressure of 
chip. 



Fig. 189. Spalling of 
tool point by pressure 
on clearance flank due 
to feeding tool into 
the work. 



226 HIGH-SPEED STEEL 

Problems in Metal Cutting. — Assuming that the machine and the tool 
and work holding devices are as rigid as possible, three other problems 
are involved in this condition: How to reduce quivering to the irredu- 
cible minimum; the development of practical maxima in cutting speeds 
in connection with methods for cooling or lubricating tools; and the 
establishment of definite cutting life periods (times after which re-grind- 
ing is to take place) for the tools. 

Pressure Variations and Chatter. — It may be well here to point out 
that what is ordinarily called chattering is not at all the same thing as 
the wave-like variation of pressure upon the tool while cutting, though 
the latter may, and often does, cause or develop into the former. If it 
were possible to obtain absolute rigidity, the variation in pressure would 
be of no consequence, so far as the effect upon the tool or the work is 
concerned; but this, as already pointed out, can be approximated 
merely, and that under the very best conditions only. In considering 
the best forms for tools (see Design of High-Speed Tools) it is shown 
that the wave lengths of the quiverings vary somewhat according to the 
thickness of the shaving, and that if a round-nosed tool be used so as to 
take a chip whose thickness varies progressively from zero to the maxi- 
mum, the tendency is for the various waves to neutralize one another; 
while, on the other hand, if the chip be taken straight and therefore of 
uniform thickness, the pressure variations easily are converted into 
actual movements of the cutting end of the tool, with bad results to 
both tool and work. Of course, even with round-nosed tools (and 
these are by no means available in every case) the pressure waves exist; 
and sometimes it becomes a problem, especially if other conditions can- 
not well be brought to the point required by highest efficiency, how to 
mitigate the evil. Particularly in taking light cuts, if there is any 
possibility of the work or of the machine springing even a little, the 
tendency will be for the tool, especially if a little dull, to jump out of 
the cut and to ride upon the unfinished surface more or less. This some- 
times will happen to a sharp tool as well. The consequences to the tool, 
saying nothing of the work, are evident. An expedient which is likely 
to help some is to modify the clearance angle of the tool slightly, so as 
to permit it to ride upon the finished flank of the piece operated upon, 
the cutting edge or extreme point being at the same time elevated very 
slightly above the center line. 

Effect of Increased Depth of Cut. — In taking such a thin chip all the 
work falls very close to the cutting edge anyway, and quivering is all 
but certain to cause the ruin of the tool in a very short time, thus occa- 
sioning frequent grindings and much loss of time. The paradoxical 
alternative is to give the tool more work to do — that is, to increase the 
depth of cut, and perhaps also the feed. This will have a tendency to 
put the tool under stress sufficient to take up all the slack in the circle 



CONDITIONS OF MAXIMUM EFFECT 227 

of parts extending from the point of the tool through the holding devices, 
machine frame or bed, and piece worked upon. It may in this case be 
necessary to decrease the speed somewhat, though this will depend 
upon the length of the cut and a number of other contingencies. Recent 
investigations seem to indicate that increased speed has somewhat the 
same effect as increased depth of cut or feed, in prolonging the life of 
the tool. 





Fig. 190. The tendency of a thick chip (deep cut) is to wear a pit or hollow some distance back of the 
edge, the latter having comparatively little work to do and standing up for a long time. In the case 
of a thin chip the wear cornea closer to the edge, which tends, therefore, to crumble or break down. 

Change Necessary in Size of Pieces. — Increasing the depth of cut, 
under the conditions indicated, obviously involves a change in the size 
of the piece to be machined. In the case of castings nothing is gained 
by excessively close molding, and an ample margin to allow a good depth 
of cut can just as well be left as not — unless possibly in small shops 
purchasing castings by the pound, where the loss in turnings might 
perhaps exceed a gain such as pointed out. In steel forgings or bars 
turned down this matter of the cost of the turnings may well be con- 
sidered, though ordinarily it will be found good practice to allow ample 
margin in any case. Unnecessary excess of size obviously is to be 
avoided also, since it involves merely the useless handling of material 
and absorption of power at the machine. In finishing malleable castings, 
it is to be remembered also, the tough or steely portion lies in and adja- 
cent to the surface, forming a skin, so to speak. If this is removed to 
any considerable depth, the casting loses much of its strength. It is 
quite safe, under ordinary circumstances, to take a finishing cut of T V 
inch on malleable castings; and this is sufficient to allow the tool to 
take a good hold. Unless they should be quite large or so peculiarly 
shaped as to be especially susceptible to warping or likely to be badly 



228 



HIGH-SPEED STEEL 



cored, the same depth is sufficient in cutting gray iron castings. Unusual 
conditions, of course, may necessitate a greater allowance. 

Relation of Cutting Speed to Chatter. — There seems to be some evidence 
that, other conditions being as carefully arranged as possible, the cutting 
speed has something to do with chatter. No extended investigation seems 
as yet to have been made of this circumstance; though it is known that 
while under a given set of conditions as to rigidity, cut, speed, and the 
like, there may be no chatter sufficient to be particularly harmful, yet if 
the speed is materially increased chattering will occur. 1 The quivering 
becomes the more important also as the cutting speed is lowered. The 
importance of this phenomenon suggests the need for a careful inquiry 
into the causes and methods of prevention, and in the meantime of 
taking note of it as a possible element in fixing speeds. 




Fig. 191. 



Correct method of supporting tool. The dotted lines show the ordinary method 
of support with too much overhang. 



Overhang of the Tool. — The need for extreme rigidity in holding the 
tool to the work has been alluded to. This condition very obviously 

involves, along with other things 
previously considered, a minimum 
overhang of the tool with respect to 
its support. Likewise it involves 
correctly formed bases in both tool 
and support. The lack of attention 
to this detail is no doubt responsible 
for much trouble. The tool base 
can of course be left moderately flat 
in forging; and some attention should 
be given to this point. The safe way, 
-,,.„.-„ „ however, is to grind the base true. 

Tool with Bottom Ground ° 

Figs. 192 and 193. Properly and improperly ground The nature of the trouble is indicated 

tool bases. Exaggerated to indicate clearly the i + i n » mm n,„ v iTi(r illnaTVQTirma 

effect of inattention to this important detail. Oy tne accompanying lllUStl atlOnS, 

1 Although Mr. Herbert's investigations, already referred to above, seem to indi- 
cate that under certain conditions increased speed tends to increase the endurance of 
a tool; whence it might be inferred that chattering would be reduced. Those inter- 
ested are referred to Mr. Herbert's presentation of his "cube law" (cutting speed 
varies inversely as the cube root of the product of the feed by the area of the cut) at 
page 1063, American Machinist for June 24, 1809. 




CONDITIONS OF MAXIMUM EFFECT 



229 



Figs. 192 and 193, in which the unevenness of the tool base is greatly 
exaggerated. 

Conditions Common to all Tools.— All that has thus far been said 
with respect to vibration and chattering applies with substantially equal 
force to all forms of cutting tools, and to those made of carbon steel 




Fig. 194. Truing up a lathe tool base on a Sellers grinder by use of a supplemental chuck-J 



as well as those of high-speed steel. The matter of overhang and 
sufficient support, for example, just mentioned, is fully as important in 
the case of rotating tools like milling cutters as it is in those like lathe 
and planer tools. It is of vital importance that the cutter be brought 
as near as may be to the spindle and arbor bearings (the shortness and 
rigidity of these having been provided for in the design of the machine) 
and that th« diameter of the cutter be small relative to that of the arbor 



230 



HIGH-SPEED STEEL 



The diameter of the cutter beyond the arbor corresponds approximately 
to the overhang of a lathe or planer tool, and the smaller this can be 
permitted, the less the liability to chatter. 

Grinding Rotary Tools. — In rotary tools, too, the matter of accurate 
grinding and keeping sharp edges is possibly of greater importance than 
in the case of others. A milling cutter which has been ground eccentric 
to a very slight amount, for example, is almost sure to chatter; and the 
more so if run at high speed. The necessity for careful grinding in ma- 
chines suitably designed for the purpose, therefore, is evident. The sub- 
ject is elaborated in another place (the chapter on grinding), and it 
is sufficient here to point out that besides the chattering accompanying 
imperfect grinding of rotating tools, drills, reamers, and the like, the 
unevenness certain to result from hand grinding involves some of the 
lips doing more work than others, taking deeper cuts, and therefore 
wearing more rapidly, and correspondingly shortening the life of a grind- 
ing — to say nothing of the effect upon the accuracy of the work. It is 
altogether likely that the unfavorable experiences sometimes heard of, 
as to finishing surfaces with high-speed tools, are very largely due to 
inaccurate grinding or to lack of foresight in providing against chatter, 
as just shown. 



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CONDITIONS OF MAXIMUM EFFECT 



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232 HIGH-SPEED STEEL 

short of it. If the matter is left to the judgment of the workman it is 
necessary to observe carefully the approach of the wear on the lip surface 
to the cutting edge, and to remove the tool in ample time to avoid ruin- 
ing the piece of work, or more likely both it and the tool. The length 
of time a tool will run without re-grinding, it may be added, is not neces- 
sarily a criterion of its excellence; and indeed it becomes one of the 
determining elements only when the tool is actually being run at its 
maximum capacity for speed. 

Lubrication or Cooling. — In the first years of high-speed steel but little 
attention was generally paid to the matter of lubrication or cooling. 
The possibilities of the new tools, as exhibited under ordinary shop con- 
ditions and without cooling, perhaps were so far in advance of what had 
been previously accomplished that the possibility of getting still better 
results was overlooked. There is, however, a considerable gain in cutting 
speed to be made through a proper cooling of the tool, or rather of the 
chip at the point where cutting takes place, a gain asserted by those who 
have given the matter attention, to be as high as 35 or 40 per cent in steel 
cutting, and from a third to a half as great in cutting cast iron. On 
many jobs such a possible gain of course is to be taken into account, and 
provisions made for delivering a cooling agent in suitable quantity and 
at the proper place. In the case of many jobs, however, such as abound 
in general manufacturing, especially where the cutting time is brief 
compared with that during which the tool is not working, no lubrication 
is necessary; and indeed in most such cases the troublesomeness of a 
stream of water or oil much outweighs any probable advantage. In all 
automatic, and perhaps in most semi-automatic machine operations, 
especially if the pieces be small, the problem is different, and lubrica- 
tion should by all means be provided, whether the material machined be 
castings or forgings. 

When Lubrication Takes Place. — While the word is in common use in 
this connection, it really is a misnomer to speak of lubrication in con- 
nection with metal cutting under high-speed conditions, except possibly 
in such work as milling. Water would have practically no lubricating 
effect; and it is quite impossible to force oil or other substance between 
tool and chip in such a way as to do much, if any good, as a lubricant. 1 
The purpose of the so-called lubricants in the main is merely to assist 
in carrying away heat from the place where the work is being done, thus 
keeping down the temperature of the cutting edge and lip of the tool 
below the point where softening will begin. In cutting with rotating 
tools, whose cutting edges are most of the time out of contact with the 
metal being cut, some actual lubrication evidently takes place, the 
friction between chip and cutter face being reduced if the exposed 

1 Although it is maintained by some, whose experience should entitle their opinions 
to weight, that lubrication really is effected to a degree worth taking into consideration. 



CONDITIONS OF MAXIMUM EFFECT 



233 



portions of the cutting blades are kept completely wet with oil or similar 
lubricant. At any rate, in milling aluminum a beautiful and clean 
finish is obtainable, there being no piling up of particles of the soft metal 
upon the face of the tool, when paraffine oil is used copiously. This is 
useful also as a lubricant in machining brass. 





Fig. 196. Correct application of oil or water. 



Copious Lubrication Necessary. — In the case of milling cutters and the 
like tools the cooling agent must be supplied in such way, by multiple 
nozzles or other device, as to keep the face of the cutter well covered, 
while at the same time it falls upon the chip at the point or line of removal. 
The latter requirement holds particularly in cutting with lathe and 
similar tools when a cooling agent is used. There can be no advantage 
in trying to force a stream under the chip and toward the cutting edge or 
point of the tool, as shown in the illustration, Fig. 196. The stream must 
be directed upon the chip just where it is being separated from the body 
of the piece, and, let it be repeated, in generous amount. The small 
streams customarily used are quite ineffective, except possibly in the 
case of very light cutting. It is necessary to deliver gallons of lubricant 
where it has been customary to deliver pints. The heavy streams serve 
another useful purpose in cases where the chips come off small or well 
broken up, in that they carry or float them out of the way. In drilling, 
for example, it is quite necessary that the stream of lubricant reach the 
bottom of the hole, not only to cool the lips of the drill, but to float up 



234 HIGH-SPEED STEEL 

the chips. In drilling tenacious material it is better to depend upon a 
feed sufficiently heavy to allow the chip to come out of the hole in one 
complete piece, if that be possible. This is especially desirable if the 
hole be deep. If it does not exceed twice or three times the diameter of 
the drill, mere flooding in oil will suffice. It is of course necessary in all 
cases to provide collection pans and suitable drainage. 

High-Speed Chip not Unique. — In this connection it may be remarked 
that the chip cut by a high-speed tool differs in no essential respect 
from that cut by a carbon tool under similar conditions. There was at 
one time much discussion of this point, based seemingly upon certain 
superficial differences which arise from the greater amount of metal 
generally removed and the higher speed at which the work is customarily 
done. 



CHAPTER XVI. 

SPEEDS AND FEEDS, AND RELATED MATTERS. 

Variables Affecting Efficiency. — The conditions under which metal 
cutting tools work are so various in different establishments, or, for the 
matter of that, in the same shop, that generalizations in respect to speeds 
and feeds are rather difficult, even when jobs are pretty well classified. 
Certain conditions unquestionably are fundamental; but in the main 
most of them vary to such an extent that confusion easily results from 
attempts to apply definite formulas, in working out standards or in 
applying them to specific operations. Mr. Taylor points out no less 
than twelve distinct variables affecting the efficiency of chip pro- 
duction, and indicates their relative importance by the ratios between 
the higher and the lower limits of speed as affected by each element 
within the ranges met with in ordinary machine shop practice, as follows: 

1. The quality of the metal to be cut — its hardness or other qualities 
affecting the cutting speed. Proportion is as 1 in the case of semi- 
hardened steel or chilled iron, to 100 in the case of very soft low carbon 
steel. 

2. Chemical composition of the tool and its treatment. Proportion 
is as 1 in tools made from tempered carbon steel, to 7 in the best high- 
speed steel. (This proportion may often be exceeded). 

3. Thickness of the shaving, measured by the actual traverse. Pro- 
portion is as 1 with thickness of T \ inch, to 3^ with a thickness of ^j inch. 

4. Shape or contour of the cutting edge of the tool, chiefly because 
of the influence it has upon the thickness of the chip. Proportion is as 
1 in a threading tool, to 6 in a broad-nosed cutting tool. 

5. Use or non-use of a cooling or lubricating agent. Proportion is 
as 1 for a tool running dry, to 1.41 for a tool cooled by a copious stream 
of water. 

6. Depth of cut or the amount by which the piece is to be reduced 
at the place of taking the chip. Proportion is as 1 with J inch depth 
of cut, to 1.36 with £ inch depth of cut. 

7. Duration of the cut or time through which the tool must last with- 
out being re-ground. Proportion is as 1 when tool is to be re-ground 
every 90 minutes, to 1.207 when it is to be ground every 20 minutes. 

8. Lip and clearance angles of the tool. Proportion 1 with lip angle 
68 degrees, to 1.023 with angle of 61 degrees. 

235 



236 



HIGH-SPEED STEEL 



9. Stiffness of tool and work. Proportion 1 with tool chattering, to 
1.15 when running smoothly. 

10. Diameter of work. 

11. Pressure upon the lip of the tool. 

12. Possible speed and feed variations in the machine, and its pulling 
and feed power. 

Generalizations Necessary. — The very fact, however, of such a multi- 
plicity of factors makes it essential to arrive, if possible, at some generali- 
zations, or at least some method of intelligently putting together the 
variables so as to harmonize them and to work for highest efficiency. 
The mere recital of experiences, perhaps useful in a way, serves small 
purpose except possibly to show the limits under a given set of conditions. 



Depth of Cut i" jl" i" •" 
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Fig. 197. Barth slide rule embodying the laws deduced by Taylor and his associates. 



Thus there is little significance in a statement that a certain tool cut 
soft steel in a lathe at a rate of 200 feet per minute. But if it can be 
shown that under a given set of conditions susceptible of approximate 
duplication in a pretty well-defined group of jobs, a tool can be expected 
to do a certain amount of work, that is to say, can take such and such 
a cut at such a speed, then something is gained, something established 
which may be used as a basis for comparison for all jobs falling within 
the category so defined. Just such a series of laws or formulas Mr. 
Taylor and his associates succeeded in working out during the course 
of their investigations, formulas easily applied to the general run of 
jobs by the aid of a simple slide rule devised for the purpose. 

Elements Affecting Economies.— The results accomplished through 
the use of the laws thus established, and the slide rule, have fully justi- 
fied themselves. And while the work upon which these formulas are 
especially based is in the main heavy cutting, that is to say, the removal 
of relatively large quantities of metal from large pieces of stock, they 
and the tables derived from them are to a very considerable extent 
available for general use in connection with the ordinary jobs found in 
general manufacturing; and a systematic use of them is sure to give 



SPEEDS AND FEEDS, AND RELATED MATTERS 



237 



surprising results. Reductions in labor cost of a half are not rare; and 
a considerable reduction in the number of workmen and of machines 
used is also to be expected in many cases. Such reductions will in large 
part depend, ordinarily, as well upon a number of other concomitants 
as upon the cutting speed. These are elsewhere considered, and it is 
desired here merely to direct attention to them as factors which affect 




Fig. 198. Barth time slide rule. Used in connection with lathe slide rule (Fig. 197) to determine time 
required for a given feed, cut and speed. 
Those especially interested in the use of the slide rules and the formulas developed for use in connection 
with them are referred to Mr. Taylor's "On the Art of Cutting Metals," and to Mr. Carl G. Barth's "Slide 
Rules for the Machine Shop as a part of the Taylor System of Management," published in Vol. 25, Trans- 
actions of the American Society of Mechanical Engineers. 

the getting out of product and which, if not taken into consideration, 
may quite nullify any advantage arising from the higher cutting powers 
of the new tools. Such factors are the size of the piece worked upon, 
the facility for transporting and storing it within easy reach of the 
workman, the design of jigs and other holding or guiding devices to 
facilitate rapidity of handling, the proper grinding of tools, careful 
inspection of parts, and perhaps others. 



238 HIGH-SPEED STEEL 

Number of Variables Reducible. — The variables affecting the actual 
cutting, while numerous, can in the average shop be considerably re- 
duced, and as a matter of fact are actually so in so far as the operations 
of any particular class are concerned. The depth of cut, for example, 
in nearly all cast-iron pieces will be about the same for all, unless there 
should be some unusual condition requiring a different. The standard- 
ization of tools eliminates the variables resulting from cutting angles and 
contour of cutting edges except in so far as it may be necessary to use 
different sizes or special tools. Likewise the composition and treatment 
of the tool becomes standardized under well-regulated management, 
and the amount of vibration in machine and tool is reduced to the 
minimum and thus also standardized, so to speak. The use or non-use 
of a cooling agent also will be definitely understood. The amount of 
pressure upon the tool is of so little influence on the cutting speed that 
it is negligible anyway. So that, outside of the factors which concern 
the powers of the machine, there I'emain ordinarily but five variants 
to take into consideration, namely, the quality of the metal being cut, 
the duration of the cut, the diameter of the piece (generally negligible) 
in lathe work, the feed, and the speed. In the engineering shop, as dis- 
tinguished from the general manufacturing shop which duplicates parts in 
large numbers, of course the variables cannot be so readily standardized. 

Taylor Standard Speeds. — The standard speeds worked out during 
the course of the Taylor investigations, given in Appendix F., as already 
indicated presume long and heavy cutting, conditions under which high- 
speed tools work at their highest efficiency. But as also pointed out, 
this class of jobs forms but a small proportion of those found in general 
manufacturing; and accordingly, for one reason or another, it is much 
of the time necessary to modify somewhat the standard speeds and cuts 
established for standard conditions and tools. Thus in a case where 
the cutting time is very brief relative to that for the whole operation, 
and the operator has all that he can possibly do to take care of the 
product anyway, a very high speed is not only unnecessary, but perhaps 
even undesirable. The gain in such case would probably be mainly 
through the saving in grindings. On the other hand there will be few 
cases, probably, where some speeding up is not only possible but desirable. 
The problem thus becomes so involved that the only safe, way is to 
accept the standard speeds, and working from these, establish specific 
ones which shall be particularly suited to the cases in hand. 

Commercially Practicable Speeds. — What must be aimed at, generally 
speaking, is the speediest removal of metal commercially practicable — 
the best speed, feed, and depth of cut, or speed and feed, if the cut is 
standard — at which the tool will work effectively and with due con- 
sideration of economical maintenance and the condition of the existing 
equipment; and all this without especial regard to the total amount 



SPEEDS AND FEEDS, AND RELATED MATTERS 



239 



of metal removed. In order to the attainment of such an end it is 
necessary first to get away entirely from preconceived notions as to cuts 
and speeds, so as to be governed by the information available through 
the experiences of others and through data collected in the shop as 
experience is gained in the applications of the new tools. 

How Conditions Vary. — The great variations in different shops, not only 
in respect to equipment but also to the material worked upon, preclude 
either the tables here given, or the standard cutting speeds from which 
the Taylor formulas were worked out, being unreservedly accepted. 
Indeed, they are for the most part entirely too fast for ordinary practice. 
The speed curves here illustrated, Fig. 199, are also based on experience, 



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25 50 75 100 125 

Cutting Speed in Feet per Minute 



The Engineering Magazine • 

Fig. 199. Curves used in one establishment for determining speeds suitable for various feeds and depths 

of cut, in turning operations. 

For milling operations add 50 per cent to the appropriate speeds indicated above, taking care to apply 
the selected speeds to feeds for which they are suited. For boring subtract 10 to 40 per cent, and for drill- 
ing and reaming, see table of drill speeds and feeds at page 249. The "small diameters" refer to those 
under 5 inches. 



and have been in satisfactory use as a basis for the cutting operations in 
a large factory for a number of years. In another plant the conditions 
might be quite different, and a different set of standard speeds might 
have to be worked out. One of the important things in connection with 
a program of maximum production, therefore, is a careful investigation 
into the nature of the material used and the establishment of a set of 
standard speeds suited to those conditions. 

Speed Meter and Stop Watch. — In the investigations and demonstra- 
tions connected with the determination of such standards, a stop watch 



240 



HIGH-SPEED STEEL 



and a speed meter are absolutely essential. A form of the latter is avail- 
able by which the speed in feet per minute can be read off directly from 
the indicator when the contact wheel rolls upon the moving surface, 
whether cylindrical or plane. The stop watch is best of the kind with 
two hands, one of which can be stopped independently of the other. 
These, in the hands of a competent person charged with the determina- 
tion of operation time for jobs and able to demonstrate unequivocally that 

the work can be done in the time set, will 
work many surprises. It is desirable of course 
also that some way be provided whereby the 
workman himself can know certainly if he is 
using the correct speed — that is, in such jobs 
as are not standardized. In such, the proper 
combination once given for obtaining the 
required speed, there should be no occasion 
for changing so long as the workman is on that 
particular operation. 

Nature of Variables in Metal Cutting. — The 
variables affecting cutting speeds, to be con- 
sidered in working out such standards, have 
been already indicated. Mr. Taylor has in his 
paper considered so fully the influence of each, 
and the reasons involved, that it does not seem 
either necessary or desirable here to do more than mention briefly the 
nature of those influences. 




Fig. 200. Warner cut meter, for 
direct reading of speeds. 
Courtesy of Warner Instru- 
ment Company. 



"3 

n 

1» 


O 






i 










































85 I>0 75 100 1:1' 

Cutting Speed In Teet per Minute 



Fig. 201. Curves showing the effect of increasing hardness in "material upon the speed permissible to 

a tool, for efficient service. 

100 is taken as the standard for moderately soft material, and 400 as about the limit of hardness as usually 
handled in manufacturing. 

Quality of the Metal. — By the quality of the metal is meant its relative 
hardness or softness and other characteristics which differentiate cast 
iron from steel and other metals, and steels of varying degrees of tough- 



SPEEDS AND FEEDS, AND RELATED MATTERS 



241 



ness from each other. The harder the material, in general, the slower 
the possible speed (note the curves in Fig. 201), this latter varying 
from 10 to 12 feet per minute in the case of chilled iron, to, say, a possible 
500 feet in the case of very mild steel. The latter speed, it should be 
mentioned, is possible only under most favorable conditions and with 
a very fine feed and cut, and is scarcely practicable, commercially. 
Under commercial conditions the quality of material varies so much, even 
in the same shop, and the variations usually are so difficult to detect 
before the material actually is put under cut in the machine, that little 
can be done ordinarily in the way of generalization. Castings, for 
example, which one day come soft and easily machined, another day 
may come exceedingly hard. Of course in a plant producing its own 
material, such differences can be reduced to a minimum, if not eliminated. 
Usually, however, because of them, it is desirable to allow some latitude 
to the workman in respect to this matter, so that in general it may be 
necessary to fix a standard speed somewhat lower than could be advan- 
tageously used regularly if the material came through of a uniform 
softness. 

Quality of the Tool. — The quality of the tool involves, of course, its 
composition, which must be adapted to the special use or be of a good 
general all-round excellence, and the proper treatment of it in hardening. 
Evidently a high-grade steel should be selected, and the tools treated 
uniformly for the same service. This will eliminate all need for consider- 
ing this as a variable. 

Use of Cooling Agent. — The use of a cooling agent will permit a con- 
siderable increase in speeds, as previously stated, ranging from 15 per 
cent or so in the case of cast iron, to 35 or 40 per cent in that of steel. 
It is advisable to calculate upon the use of a cooling agent wherever feas- 
ible — that is, wherever the cost and annoyance would not overbalance 
the gain. 

Length of Cutting Run. — In general work the cuts are short, and thus 
allow the tool to cool off between times. The time during which such 



TABLE IX. 



Showing how much a high-speed tool must be slowed down in cutting speed in 
order to have it last a long time without regrinding. 



Given the proper cut- 
ting speed for a cut 
lasting 


to find the speed for a 
cut lasting 


divide by 


or multiply by 


20 minutes 
40 minutes 
20 minutes 
40 minutes 
80 minutes 
80 minutes 


40 minutes 
80 minutes 
80 minutes 
20 minutes 
40 minutes 
20 minutes 


1.09 
1.09 
1.19 

0.92 
0.92 
0.84 


0.92 
0.92 
0.84 
1.09 
1.09 
1.19 



Adapted from Taylor. 



242 HIGH-SPEED STEEL 

a tool will run without re-grinding, therefore, is likely to be somewhat 
longer than if it cut continuously. The establishment of a standard 
time after which tools in general should be ground is difficult except when 
they are run continuously at maximum speed, and for the most part it 
will be impossible to lay down hard and fast rules for this factor. In 
the main it is safe to leave this to the judgment of the workman. Espe- 
cially if he is working by the piece or for a premium he will quickly learn 
to note the condition of the cutting edge and to take care that the tool 
is ground as often as necessary — not grinding the tool himself, be it 
remembered, but merely setting up a sharp one which he will have at 
hand for that purpose. 

Clearance and Cutting Angles. — No important improvement seems 
to have been made upon the Taylor standard tools (though it is well to 
bear in mind what is said elsewhere in reference to the Hartness type 
of tool), so that in the matter of clearance and cutting angles, as well 
as contour of cutting edge, it is well to undertake few changes, if any, 
except perhaps in the case of jobs requiring tools of special form. 

Effect of Chatter. — The possibility of any considerable amount of 
vibration will reduce the attainable cutting speed by something like 
15 per cent. The purpose of course should be to eliminate this item 
as far as possible through the use of machines suited to the work and not 
worn beyond hope. In the same connection the possible pulling and 
feeding power of the machine must be considered. If inadequate, 
evidently the speed, and more than likely also the feed, will have to be 
reduced to meet the condition. The use of a steady rest is advised for 
all work of any considerable length. 

Depth of Cut Problems. — The depth of cut will, for the most part, 
be dependent upon the class of work done in the shop, and as pointed 
out in another place, may need to be increased, a suitable allowance in 
the size of the piece being made in this case, so as to overcome chatter 
or riding of the tool. 

Factors Affecting Feed or Traverse. — Traverse or feed will be governed 
to some extent by the possibilities inherent in the machine, but a good 
deal also by the surface required. The limitations are rather narrow, 
usually, in a given shop. A round-nosed tool, such as will probably 
be used for most operations, when cutting with a heavy feed leaves a 
correspondingly rough surface. And since probably most of the work 
of the kind now under consideration must be done with a single cut, 
it is necessary to select a feed or traverse which will leave a sufficiently 
smooth surface. Anywhere from one-sixteenth to one-eighth inch feed 
will do this, unless the tool be a very small one. Obviously the larger 
the curve of the cutting edge, the coarser the feed may be in the case of 
lathe and similar tools. A variation so great as this would seem to make 
a considerable difference in the possible cutting speed; for this depends 



SPEEDS AND FEEDS, AND RELATED MATTERS 



243 



=\^ 






oer Min.olfcJ 
















5i^ 


150 






1 














i 


130 






1 




1 
















1 




1 












120 
110 
100 






V 1 

VI 












































































90 










































80 






! 




















1 




N s ^ ! 












7U 






1 




































00 


' ^ 




1 

1 
























i 








Soft St 


ikl. 


50 
40 
SO 










J 




















i 




















I 






























\ i 


20 




















i 




















1 


10 




















Ha 


•d Steel 























Fig. 202. Relation of economical speed to cut and feed. Steel in steel cutting. 




Fig. 203. Relation of economical speed to cut and feed in cutting cast iron. Both figures 
adapted from speed sheets made by Samuel Osborn & Co., Ltd. 



244 HIGH-SPEED STEEL 

upon the feed and cut to a very important extent, as already seen. In 
fact it would, under conditions allowing maximum effects, make a reduc- 
tion of a fourth to a third in the speed. As a matter of actual practice, 
however, under the conditions here considered, the speeds will rarely, if 
ever, be the maximum possible, so that a variation of the magnitude 
indicated is of no particular consequence — though of course the con- 
tingency of a possible necessity for changing the speed must not be 
overlooked. Obviously the power available must also be considered. 
In milling operations the table traverse or feed has in ordinary practice 
been ridiculously small, just as it has in the case of drilling and similar 
operations; though until recently it has been not far below the possi- 
bilities of the machines in use. The real need for giving each cutting 
blade enough work to do to keep it in the metal rather than riding over 
it at times, seems to have been little regarded. It is quite as necessary 
for the blade of a milling cutter to get a good " hold," so to speak, upon 
its work, as it is in the case of a lathe or similar single cutter tool. The 
traverse of course is interdependent with the number of cutting blades 
and the speed of cutting. About 0.01 inch per tooth per revolution is 
correct for most work, though with large cutters and plenty of chip 
clearance considerably more is allowable. 

Phenomenal Results. — A tool steel vendor reports having obtained a 
speed of 232 feet per minute, \ inch cut and \ inch feed, on cast iron; 
a large user of high-speed steels mentions that he has seen a tool running 
for a full hour, on cast iron, at the rate of 125 feet per minute, removing 
scale; and another cutting steel at the rate of 270 feet per minute for 
nearly 30 hours at a stretch. Indeed it has been reported that a tool 
has cut steel for some time at the rate of 500 feet per minute. Other 
phenomenal performances also have been mentioned elsewhere. Now 
all these, and similar performances, are very interesting as showing 
something of the powers of the new tools. But they are not commercially 
practicable. In turning castings, as they come ordinaril}' - , 65 to 70 feet 
per minute is as high a speed, with usual feeds, as can be maintained con- 
tinuously without too frequent grin dings of the tool. Light cuts may be 
taken up to 100 feet. Making allowance for variations in hardness and 
the powers of the machines likely to be used, however, 50 feet is more 
likely to be satisfactory as a basis to work from. This is easily double 
what we have been accustomed to under the old conditions. Light finish- 
ing cuts have been taken with a satisfactory degree.of accuracy as rapidly 
as 75 to 85 feet per minute, though something rather lower will usually be 
found better on the whole. At these rates the speeds for soft, medium, 
and hard irons would be respectively about 90, 50, and 25 feet; and for 
moderately heavy cuts about 60, 30, and 20 feet. These speeds of 
course will be modified according to the size of the tool, the precise feed 
and depth of cut, and the rest of the variable conditions. Working on 



SPEEDS AND FEEDS, AND RELATED MATTERS 245 

pieces of large diameter, for example, the speeds may be increased 10 to 
15 per cent. This is not only because in such pieces the direction of the 
cut changes less rapidly, but because even in sand molds small pieces 
have a tendency to chill more or less, and the cut in work of this sort 
also being customarily lighter than on heavy pieces, the tool is actually 
working on iron averaging a good bit harder than if cutting on a large 
piece. 

Turning Chilled Iron. — Chilled iron can be turned at anywhere between 
3 and 10 or 12 feet per minute. The rate of cutting is of small conse- 
quence, since most of the time is used in changing the tool anyway. A 
tool that will hold up at 3 feet will be almost certain to do quite as well 
at three or four times that speed. It should be remarked in passing 
that the turning of chilled rolls is accomplished by the use of tools of 
special design, ordinary tools being of little use generally. The common 
method is to use a square section of steel for the tool, grinding the longi- 
tudinal edges to sharp right angles for cutting edges, and rigidly wedging 
this unique cutter against the surface of the roll. The tool is not trav- 
ersed, but its position is changed each time it has finished a section of the 
roll. For cutting grooves and spirals, the end of the section instead of 
the longitudinal edge is forced into the iron. 

Speeds in Steel Turning. — In steel cutting, speeds have been attained 
very much higher than on cast iron. The reasons for this have been 
already assigned. On mild steel light cuts at 80 or 90 feet are not 
infrequently taken, and 100 feet or even more are sometimes used. 
Taylor's tables allow 128 feet per minute on soft steel with a f inch tool, 
cut | X | inch. These are not usually practicable commercially except 
under conditions allowing maximum effect. Roughing cuts, say about 
f X s 3 5 inch, with a 1-inch tool, can be taken at a maximum of about 
100 feet per minute on mild steel, while 70 to 75 feet is considered good 
practice. Medium steel, say 3 to 5 point carbon, under customary 
conditions, can be cut at approximately 70 and 50 feet for light and 
heavy cuts respectively, though rather less is likely to be more satis- 
factory; while hard steel, say 7 point carbon and above, is not usually 
cut faster than about 35 feet in light cuts (say about | X i inch) and 
25 feet in roughing. 

Cutting Malleable Castings. — In malleable castings 80 feet is about 
all that can be expected on small pieces, where light cuts are taken. 
Heavy cuts, as already shown, are to be avoided in castings of this kind. 
On large pieces the speed may under favorable conditions be made as 
high as 90 or even 100 feet per minute. If a cut as deep as \ inch be 
taken for any reason, the speed will be nearly half that indicated. 

Brass, Aluminum, and Alloy Steels. — Speeds for brass and other soft 
materials will be somewhat greater than those suitable in cutting steel. 
The alloy steels, like chrome and nickel steel, now coming into large use 



246 



HIGH-SPEED STEEL 



for machinery parts, vary so greatly in characteristics that it is quite 
impossible to lay down at present any general statement as to permissible 
cutting speeds. Aluminum can be worked at about four times the speed 
and double the feed possible with mild steel. 




Fiq. 204. Use of multiple tools in turning cast-iron cone pulleys. Speed on largest step t 

120 feet per minute. 

Use of Multiple Tools. — The use of double or multiple tools allows a 
distinct gain in speed in turning operations. The interrelation of speed 
and feed makes it necessary to reduce the former when the latter is 




Fig. 205. Lathe fitted for rapid roughing and rapid finishing. 

increased. A single tool taking a chip f inch wide (traverse f inch per 
revolution) must run considerably slower than two tools, each feeding 
at fV inch per revolution. Doubtless there is some difference in the 
amount of power absorbed; but this is a matter of relative insignificance. 
The advantage of using multiple tools in long cuts has never been recog- 



SPEEDS AND FEEDS, AND RELATED MATTERS 



247 



nized as it should be. The advantage under the new conditions should 
be evident enough to warrant a large use of them, especially in operations 
involving the removal of large quantities of metal. 

Reduction of Speeds in Certain Operations. — It has doubtless been 
observed that the discussion of speeds and feeds thus far has been con- 
fined for the most part to turning operations. With the possible excep- 
tion of milling, where the cutting edges work intermittently and are for 




Fig. 206. 



Multiple tool carriage, as applied to "Lo-Swing" lathe. See Fig. 207 for data as 
to this particular job. 



the greater part of the time exposed to the cooling effect of the air or a 
cooling agent, these permit greater speed than any others in metal cutting. 
It is therefore necessary, in setting standard speeds for other kinds of 
work, to make allowance for the variations in conditions — ■ variations 
not provided for in most tables of cutting speeds now available. Inter- 
nal cutting with a boring bar, for instance, must be considerably slower 
than external turning of the same diameter. In outside cutting the 
tool may have ample clearance, or it may even ride upon the finished 
flank — a condition impossible in the case of internal cutting. Further- 
more, in order to secure a sufficient clearance it is necessary to give the 
cutting edge a more acute angle, or else to give it less rake than that of 
the corresponding standard tool. Either condition involves a slower 
cutting speed, the reduction being something like 10 to 15 per cent 
if the bar is exceedingly rigid. If not, the loss is more likely to be nearer 
40 per cent. 



248 



HIGHSPEED STEEL 



As to Drilling. — Something of the same sort is true of rose reamers, and 
of twist drills also, to some extent. In drilling, little attention need be 
paid to this point, however, since but few machines are now in use which 



-21H 



K — 3--X2}£>K 



~ 



JL 



Pinion Shaft 



-\VA- 



->k-2><H 



H 



EP 



Roller Follow Ttest 



ist Operation 




Pfh^ 



D 



n 



Roller Steady Best 




Fig. 207. 



2nd Operation 

Cutting Time for ist Operation no R.P.M. and Ho Feed 4 Min. 

" " << 2nd u << <( <i « 3 Min. 

Estimated Time for Cutting in with Tools, Placing Bars, Etc. 6 Min. 

Total Time Required 13 Min. 

Performance in rapid reduction, in machine building, by use of multiple tools. 
Fitchburg Machine Works. 



Courtesy of 



will effectively speed a drill to the limit of efficiency. The most satis- 
factory practice in drilling average cast iron allows a peripheral speed 
of about 65 to 70 feet per minute, though under exceptional conditions 
still higher can be used to advantage. The feed per lip per revolution 
may vary from 0.008 to 0.02 inch, according to the size of the drill and 
the conditions, with respect to rigidity and powering of the machine and 
the cutting angle, of the drill. It must in any case be heavy enough to 
permit the drill to bring up a good chip; otherwise there is likelihood of 
the latter being pulverized and then acting as an abrasive to grind away 
the cutting edges. As with lathe tools working with exceedingly fine 
cuts, a drill will stand a higher speed when taking a moderately heavy 
cut than when taking almost none. The frequent breakage of drills, 
occurring just as the point emerges from the metal and commonly 
ascribed to high speed or excessive feed, really is due to spring or slack 
in the machine; and the remedy is not in reducing. the speed or feed, but 
in strengthening the machine. In the great majority of jobs as at present 



SPEEDS AND FEEDS, AND RELATED MATTERS 249 

TABLE X. SPEEDS AND FEEDS FOR DRILLS. 



Size of Drill. 



*■ 

& 
f 

A 
I. 

*• 
I- 
i. 

f 
1. . 

if 
if 
if- 
ij. 

if 

2.. 



Revolutions per Minute. 


Steel. 


Mall. 


Cast. 


Brass. 


Tool Steel . 


4015 


4620 


4820 


7650 


1970 


1850 


1925 


2220 


3515 


906 


1380 


1610 


1650 


2810 


675 


1040 


1190 


1250 


1970 


506 


855 


982 


1028 


1620 


420 


782 


806 


836 


1330 


342 


604 


688 


720 


1140 


295 


527 


605 


632 


1003 


258 


425 


488 


512 


807 


210 


347 


410 


420 


666 


173 


300 


346 


360 


568 


146 


260 


298 


312 


495 


128 


228 


264 


276 


436 


112 


215 


248 


260 


410 


106 


200 


230 


238 


380 


98 


178 


205 


216 


342 


92 


154 


173 


180 


290 


73 


130 


150 


156 


246 


64 



Feed per 
Revolution. 



.001-. 002 
.002-. 004 
.003-. 006 
.004-. 008 
.004-. 008 
.005-. 010 
.005-. 010 
.008-. 016 
.008-. 016 
.008-. 016 
.008-. 016 
.010-. 020 
.010-. 020 
.010-. 020 
.010-. 020 
.010-. 020 
.010-. 020 
.010-. 020 



This table is based on a peripheral speed of 60 to 65 feet per minute in soft steel, in the medium 
diameters. As the diameters decrease, the peripheral speed is increased, this being good practice. If 
run without lubricant, the speeds should be reduced 15 to 20 per cent. The feed is preferably the 
lighter one given, though under good conditions the higher gives good results. For rose reamers, and 
for threading dies and taps, about half the speeds indicated are to be used. 



done, the lack of positive feeding device on the machine makes the feed 
a matter of judgment on the part of the operator — or, more likely, a 
matter of his strength — with the consequence that efficiency is lost. In 
drilling holes of small diameter the feed is all but certain to be too heavy, 
and the reverse in large sizes. It would seem more than desirable that 
all machines be fitted up with positive feed devices to insure the best 
results. 

Speeds and Feeds for Rose Reamers. — Twist drills have ample rake at the 
cutting edge, and therefore can be run considerably faster than reamers, 
which latter all but invariably have no front rake to the cutting blades. 
About half the speed allowed to drills is usually satisfactory with ream- 
ers and similar internal cutters. In using the table of speeds for drills to 
determine reamer feeds it must be remembered that the feeds given are for 
two-lipped drills, whence it is necessary, in order to get the correct feed 
per revolution for a reamer, to take half the product of the feed given 
for the specified diameter by the number of flutes or lips; or, putting it 
F X L 



another way, 



2 



required feed per revolution, where F and L 



respectively are the feed stated in the table and the number of cutting 
lips. Concretely this would give, in the case of a 2-inch six-fluted 



250 HIGH-SPEED STEEL 

reamer, cutting cast iron, the following: Feed per revolution = — — 

= 0.03 inch. It is not advisable to use on reamers the higher feeds given 
for drills. This matter is, under ordinary conditions, of greater impor- 
tance than in the case of drills, because reamers customarily are used on 
machines provided with positive feed, and hence the amount of feed can 
be regulated as it should be. 

Milling Operations. — The highest practicable speeds in metal cutting are 
obtained in milling operations, though the feeds have until recently been 
absurdly slight. The intermittent nature of the cut, allowing the teeth 
or blades to cool between times, has something to do with the higher 
speeds permissible. Compared with drilling, the gain is something like 
50 per cent. The peripheral speed, at a depth of cut and table traverse 
per tooth per revolution of \ inch and 0.01 inch respectively, which may 
be taken as a maximum when working on average cast iron, is about 
90 feet per minute, though considerably higher speeds have been main- 
tained. The customary speeds are rather lower, especially if no lubricant 
be used. This basis is rather high for a machine such as is ordinarily 
in use, and is likely to stall it. With powerful machine and properly 
designed cutter, however, it is none too high, and is by no means remark- 
able compared with some everyday performances like cutting nickel- 
chrome armor plate at 75 feet and nickel steel at 80 feet. It must be 
said, however, that cutting like this last mentioned could not be done 
except on machines thoroughly adapted to the work. In taking finish- 
ing cuts it is customary to use speeds considerably slower than those 
indicated. 

Of course, as in the case of other tools, allowance has to be made for 
the kind of material worked upon, in the determination of practicable 
peripheral speeds. Those found to be generally efficient and productive 
are : Cast iron, medium, from 90 feet per minute down; malleable, 85; 
mild steel, 75; tool steel, 35; brass, 140, aluminum, 500 or more. The 
table traverse in the case of brass and aluminum will of course be 
advanced to correspond with the high speed. Speeds for the several 
grades of cast iron and steel can be derived from the tables given for 
turning operations, the figures above being taken as starting points. 

Taps and Threading Dies. — Taps and threading dies may be run as fast 
as the material can be taken care of; and this will rarely exceed half the 
speed indicated in the table of speeds and feeds for drills. On some 
kinds of material even less than half is possible. Even so, however, there 
still is usually a considerable gain over the output of carbon steel tools. 

Planer and Shaper Speeds. — As to planer and shaper work, and other 
cutting of like nature, it is necessary to point out only that the tools 
will carry all the speed, and in general all the cut, that the machine in 
use may be capable of pulling. Some recent performances indicate the 



SPEEDS AND FEEDS, AND RELATED MATTERS 251 

possibility of an 80 feet per minute planer cut, though this does not seem 
to have been accomplished in a commercial way. Sixty feet, however, 
has been carried as a regular performance; and this may for the present 
be accepted as a maximum record in regular work, while 50 feet, with a 
high-speed return, is about as much as can be expected on any recipro- 
cating machine — and this only on one of strictly modern design. Older 
types of machine cannot give much more than half as high a speed 
without much racking and burning up of belts. 



CHAPTER XVII. 

FUNDAMENTAL CONSIDERATIONS IN THE DESIGN OF 
THE NEW TOOLS. 

Factors in Efficiency. — The prime motive in machine and tool design 
obviously is efficiency. One productive apparatus is preferred above 
another because it turns out work more economically while still not 
sacrificing the accuracy or quality requisite. What is called efficiency, 
then, is usually considered to mean a maximum production of satis- 
factory quality at minimum cost. In most instances the chief element 
in cost is labor: which is to say, time. Wherefore it is often assumed 
that the tool or machine which works most rapidly is of necessity the 
most efficient. Nevertheless, there are other considerations which are 
not infrequently quite as important as time, or which at any rate affect 
the time of production to a very great extent. The proper hardening 
and tempering of a high-speed tool, for example, has been previously 
mentioned. Unless given the treatment suited to the required service, 
the very best of high-speed steel will fail to do efficient work. So also 
the machine in which, and the material upon which the tool works, 
both affect its relative efficiency. A further important factor,, in the 
past very little regarded, is the design and shape of the tool and the 
nature of its cutting edge — when it has one. 

Heavy Stock for High-Speed Tools. — The need for greater cross- 
section in high-speed tools is referred to elsewhere. The steel itself is 
much stronger than carbon steel, and is therefore better able to with- 
stand the stresses and shocks incident to their work. The increased 
strength, however, is not nearly in proportion to the increase in the 
stresses involved in the greater feeds or speeds or both, in the case of 
cutting tools. If properly supported, a section from one-fourth to one- 
half greater than that customary in carbon tools is generally sufficient 
allowance for lathe tools of standard form and others similarly supported. 
In special or intricate shapes of course the allowance would better be 
somewhat greater, as also where the requirements may be especially 
exacting. If run at speeds not much greater than those customary 
with the old tools, and without much heavier cuts, of course there need 
be no increase in cross-section at all. All forms of these tools with slender 
necks or much side bend are to be avoided, since they tend to spring 
and twist under the heavy work, and are almost sure to chatter even under 
the most favorable conditions. 

252 



FUNDAMENTAL CONSIDERATIONS IN THE DESIGN OF TOOLS 253 

Special and Oblong Sections. — Special sections have been rolled, re- 
sembling I bar and other structural forms, intended to economize metal 
and afford greater strength in proportion to the weight than the rectan- 
gular section commonly used. Any advantage such sections may have is 
confined to tools made directly from the bar merely by grinding the 
required nose, these forms not being well adapted to forging — though 
they are sometimes slightly bent. It has been shown that while a very 
dull tool may at times require as much power to feed it as to drive, under 
normal conditions the side pressure is generally not more than 20 per 
cent of the down pressure, and usually is considerably less. The longi- 
tudinal diameter of a tool stock, therefore, can well be less than the 
vertical, though the amount of difference should not be great enough 
to allow a tendency to spring sidewise under abnormal conditions or to 
turn in the post or holder. The happy medium in practice appears 
to be, as recommended by Taylor, about l\ vertical to 1 longitudinal 
unit. The length obviously should be such as to permit proper fasten- 
ing in the post or holder, and also to allow re-fettling a suitable number 
of times. The length adopted by Taylor is approximately: Length = 
14 X Width + 4 inches. 

Contour of Cutting Edge. — Chattering, as explained elsewhere, de- 
pends upon a number of things; and one of these, assuming that the 




z^ff^raHwmGABovL 



Fig. 208. Analysis of shaving, showing varying thickness at different points, thus tending to avoid 
chatter while at the same time minimizing work at the point or part taking the finishing cut. 

tool is of such form and stiffness as not to spring under pressure, is the 
lack of correct angle and outline of the cutting edge. The experiments 
of Dr. Nicholson have shown that no matter how rigidly tool, machine, and 



254 



HIGH-SPEED STEEL 



work are brought together, the cutting of a shaving or chip is accom- 
panied by a more or less regular variation in the pressure upon the lip 
of the tool. The thinner the shaving, the shorter the wave-lengths 
corresponding to the variations in pressure. Evidently, then, if the 
thickness of a particular cut is uniform, that is, if the cutting edge of 
the tool is straight, there will be a tendency for the waves of pressure 
variation to emphasize any vibration in the tool, work, or machine, 
and thus produce chattering and consequently a badly finished surface. 
If the tool has, however, a curved cutting edge, so that the thickness of 
the chip varies (note Figure 208), especially if it varies from nothing at 
one side to the maximum at the other, the tendency will be for the 
various waves of pressure to counteract and nullify each other instead 
of emphasizing other tendencies just mentioned. 

There are other reasons also why a curved cutting edge is preferable 
to a straight one in heavy and rapid cutting, if not in all cases, the most 
important of which Mr. Taylor has shown to be that it allows that 



SIZE OF TOOL 




FEED 

Fig. 209. Relation of size of tool (breadth of cutting nose) to thickness of chip at point of tool and there- 
fore to maximum cutting speed. Limitation of feed (in respect to smoothness of finish) by decreasing 
size of tool is also shown. The relative thinness of the shaving taken by the larger tool is espe- 
cially noticeable at the shallower cuts. After Taylor. 

portion of the tool taking the finishing part of the cut to make a very 
thin chip. This part of the cutting edge under these conditions is less 
affected than that taking the heavy part of the cut, and continues sharp 
and in good condition for leaving a clean finish even after the rest of 
the cutting edge has become damaged. 

Broad-Nosed Tools. — Mr. Taylor points out also that the amount of 
the curve has much to do with the effectiveness of the tool, showing that 



FUNDAMENTAL CONSIDERATIONS IN THE DESIGN OF TOOLS 255 



curved tools with broad noses would be best, but for the tendency to 
chatter. -The amount of curve to be given a standard tool is affected 





CLEARANCE 6 
BACK SLOPE 8 
SIDE SLOPE 14' 




Fig. 211 



Taylor stand- 
ard tool for heavy 
feeds. 



Fig. 210. Examples of Taylor broad-nosed tool. 

by several conditions besides this tendency in broad-nosed tools to 
chatter, among them these: the size of the lathe and of the work to be 
turned, the depth of cut required, the amount of feed 
permissible, the speed possibilities, the smoothness of 
finish (relative amount of absence of ridges and fur- 
rows) required, the nature and resistance of the ma- 
terial cut, and any special conditions that may happen 
to be involved in particular cases. The maintenance 
of standard tools, in the ordinary shop, in sufficient 
variety to meet with highest efficiency all the possible 
combinations or conditions is manifestly impossible, 
even were it not necessary to sacrifice efficiency in one 
particular in order to more than balance up through some compensating 
modification in design. 



VTmi^V'n s JotJSlS-- /- 

l ';t ■■ a i i * * * s<$r>+ -f~] 

£*P LET WIDTH OF TOOL=A" J 

AND RADIUS OF POINT=R 

THEN u 

FOR BLUNT TOOL R^A-JL 

FOR SHARP TOOL R=\ A-% 



For cutting hard steel and 
cast iron, these tools are 
ground to the following an- 
gles : Clearance angle 6°, 
back slope 8°, side slope 14°. 

For cutting medium steel 
and soft steel, these tools 
are ground to the following 
angles: Clearance angle 6°, 
back slope 8°, side slope 22°. 



Fig. 212. Outline of cutting edge, Taylor standard round-nose tool. 

Standard Angles for Cutting Tools. — The matter of lip angle (for 
definitions of terms used in connection with lathe tools see Fig. 213), 
for instance, while not of the degree of importance sometimes attached 
to it, has some influence upon the permissible cutting speed and the 
excellence of the work done, and a very, considerable influence upon the 





256 



HIGH-SPEED STEEL 



lasting quality of the cutting edge and the stresses imposed upon tool 
and machine. The clearance angle, from the heed for the greatest 
possible support of the cutting edge, must be small, say about 6 degrees, 
as in the Taylor standard tools; while not yet so small as to prevent the 



I HE6.1- OF 



TOOl 
Z2TEARW* / 





Fig. 213. Key to terms used in connection with lathe tools. From Taylor, 







i 8 r 



"-i. 



HARD STEEL 
AND CAST IRON 




SOFT STEEL 



Fig. 214. Angles for cutting cast iron and hard steel compared with those for work in soft steel. 

tool being readily fed into the work and to cause the flank of the tool 
to rub too much against the finished work. The lip angle of a tool will 
depend in a considerable degree upon the work it is to do. A small 
angle reduces the pressure upon the tool and perhaps allows some in- 
crease in speed; but other considerations, chiefly the necessity for having 



FUNDAMENTAL CONSIDERATIONS IN THE DESIGN OF TOOLS 257 

a sufficiency of metal at the cutting edge to carry away the heat generated, 
and at the same time stand up to the work without crumbling, indicate 
a rather obtuse angle. The harder the metal being cut, the more blunt 
the cutting angle should be, the general rule being that the angle should 
be just as sharp as it may be without crumbling or spalling so rapidly 
as to impair the efficiency of the tool. The angles recommended by 
Taylor for the several typical classes of work ordinarily found in a shop, 
are given as follows: 

Cast iron and harder steels (say 0.45 carbon and up), lip angle 68 
degrees; clearance 6 degrees; back slope 8 degrees; and side slope 14 
degrees. 

Softer steels, lip angle 61 degrees; clearance angle 6 degrees; back 
slope 8 degrees; side slope 22 degrees. 

For cutting chilled iron, 86 to 90 degrees lip angle. 

Tire steel, and similar hard steels, lip angle 74 degrees; clearance 
angle 6 degrees; back slope 5 degrees; side slope 9 degrees. 

Extremely soft steels (say 0.10 to 0.15 carbon), lip angle about 61 
degrees, and perhaps less. 

Relation of Side and Back Slope. — It is to be noted that the side slope 
recommended in these tools is considerably greater than the back slope, 
and varies also considerably from the angles heretofore customarily 
employed. The relatively steep side slope allows the tool to be much 
more frequently ground without weakening it, allows the chip to slide 
off in a line avoiding the tool post or holder, helps to correct the tend- 
ency of the tool to side deflection by throwing the pressure line within 
the base of the tool, and reduces the feed pressure. The greater blunt- 
ness in tools for cutting soft cast iron, compared with those used in 
cutting soft steel, is also noteworthy. 1 

Hartness Type of Lathe Tool. — Excellent results are obtained in many 
shops through the use of lathe tools of an entirely different type from 
those just described, cutting the metal in a way essentially different. In 
these tools, designed, it seems, by Mr. James Hartness in connection 
with his Lo-Swing lathe, there is no clearance, no forging, and the cutting 
angles may be of almost any degree of acuteness, in most cases much 
smaller than is customary. The cut is taken straight sidewise, the tool 
feeding along the periphery of the rotating work, and slicing off a band 
of a depth and thickness corresponding to the feed and depth of cut. 

1 Space does not permit here a discussion of the various experiments and experi- 
ences furnishing the reasons for the standards (those recommended and used by Taylor 
as standard cutting tools) given above. Any one caring to pursue the subject further 
will find much of interest in Mr. Taylor's address or report "On the Art of Cutting 
Metals," already mentioned.. Another paper of very great interest, by Mr. James 
Hartness, considering the nature, cutting angles, and utility of the type of tools re- 
ferred to in the following paragraph, was read before the same society at the 1908 
meeting. 



258 



HIGH-SPEED STEEL 



The ribbon chip is removed at the front (that is, by the edge of the tool) 
by real cutting, the nose of the tool being forced into the metal and 
wedging it away from the main mass; while at the finished surface of the 
work the action is comparable to that of shearing, leaving, however, a 




Fig. 215. Examples of Hartness tools, with sharp cutting angles. 

satisfactory finish surface. The end or nose of the tool rides against the 
flank of the finished piece, and by giving the cutting edge and lip a suit- 
able positive or negative back slope, the pressure against the tool, 
tending to force it out of the work, can be minimized; at the same time 




Fig. 216. Characteristic chips. Those at the left were made by a diamond point tool having 70 degrees 
cutting angle. Chips at the right made by a no-clearance tool, 45 degrees cutting angle. From "Ma- 
chine Building for Profit," by James Hartness. 

the cutting angle can be so selected that the tool will actually feed itself 
into the work, entirely eliminating the feed pressure, the feed drive 
being required mainly in starting the cut and in maintaining it uniform. 
By mounting the tool in a holder or post in such a way as to afford some 
freedom of movement, lateral vibration in cutting is almost if not en- 



FUNDAMENTAL CONSIDERATIONS IN THE DESIGN OF TOOLS 259 

tirely eliminated, and the cutting edge of the tool therefore is unimpaired 
by reason of chattering, which is relatively a much more important 
factor in its destruction than heat is, in tools not employed in exceed- 
ingly high speed or heavy feed cutting. By suitably selecting the cutting 
angles the tools also become, to a certain extent, self-sharpening, the lip 
and flank riding against the cut surface wearing along with the edge 
itself, though perhaps less rapidly. 

For many kinds of work such tools are run with faces nearly straight, 
on the principle of the side tool. In other cases it is found desirable 
to give the tool a slight round. In turret lathe practice, when working 
on bar stock properly supported by back rest, the corner of the tool is 
left nearly or quite square. 

Utility of Hartness Tools. — Tools of this type are inexpensive to 
make and seem to have a rather wide range of usefulness in the ordinary 
metal-working shop in connection with appropriate forms of turret 
lathes doing repetitive work of moderate size and not of the kind where 
the so-called rapid reduction, the speedy removal of relatively large 
quantities of metal, is necessary or economical. In diameters under, 
say 3^ inches, work up to 3 feet in length can be advantageously turned 
with such tools, while in diameters ranging from that given up to, say 
20 inches, the lengths conveniently turned are up to nearly a foot. Diam- 
eters smaller than one inch, or possibly a little less, are riot so well adapted 
to the use of these tools. 1 

The Problem. — Taylor Standard Tools. — The problem in designing 
lathe tools, and those of similar use, is in the main one of so harmonizing 
the various elements affecting the form, the shape of the cutting edge, 
and the lip angle, that the highest all-round efficiency shall be obtained 
with a minimum number of different tool forms. The tests and expe- 
riences of Mr. Taylor and his associates, and of many others who have 
adopted his standard shapes, leaves no doubt as to their all-round 
efficiency in roughing and rapid reduction work. They require con- 

1 The experiences and observations of Mr. Hartness have resulted in his formulating 
the following conclusions with respect to the advantages of this non-clearance type of 
tool: 

Relieves the edge from one-sided pressure. 

Prolongs the life of the cutter by allowing abrasion on its face without producing 
negative clearance. 

Converts the lip angle into a cutting angle, which for a tool of given form consti- 
tutes a gain of from 5 to 10 degrees in cutting angle. 

Extends the range of the side tool (a tool of this type is really a side tool), which 
gives the minimum stress. 

Makes possible the use of acute-angled tools, thereby increasing the output of 
machines which have been limited by lack of pulling power. 

The reduction of the cutting and separating stresses increases the accuracy (or 
output, which is generally interconvertible with accuracy) on nearly all lathe work. 

This reduction of stresses also increases the output, which has been limited mostly 
by the frailness or slenderness of the work. 



260 



HIGH-SPEED STEEL 





Fig. 217. 



Type of lathe tool much used on the continent, but not equal in efficiency to tools requiring 
more forging and permitting a greater number of grindings. 




Fig. 218. Detailed dimensions of Taylor standard one-inch round-nosed roughing tool. Forged outline 

shown by dotted lines. 



FUNDAMENTAL CONSIDERATIONS IN THE DESIGN OF TOOLS 261 

siderably more forging than tools customarily used; but this very thing 
is the result of a compromise in design whereby many grindings with 
few dressings are possible before re-fettling and re-hardening become 
necessary. 1 Of course in the ordinary run of shops, where the variety 
of work is large, there will inevitably be many jobs which can be better 
done with tools of other or of special design. It is well, however, to bear 
in mind always that a multiplicity of tool forms greatly complicates the 
tool problem; and that when all things have been taken into account 
it may after all be quite as economical to use a standard as a special tool. 
Tool-Holder Stock. — In the early days of high-speed steel the tendency 
was to use it very sparingly, and for the most part in the form of tool- 
holder stock. This method permitted the use of a minimum of stock 
(and a consequent minimum expenditure, as it was thought) and neces- 
sitated little expense in tool making, since the stock was usually bought 
unannealed and was put to work after nothing more than grinding to 
shape. The lightness of the stock which could be used was a manifest 
shortcoming, which was soon remedied by the design of other tool 




Fia. 219. A patented tool holder which allows close contact of tool and holder 
and insures an unusual degree of rigidity in the tool. 

holders large enough and heavy enough to meet the requirements in 
this respect. The use of the unannealed stock, without treatment, has 
been found to be unsatisfactory; and the usual practice now is to treat 
tool-holder stock precisely as other tools are treated except that little 
forging, if any, is attempted. For many uses, especially for light cut- 
ting, the use of such stock, in suitably designed holders, is permissible 
and gives good results, though usually not so good as can be otherwise 
obtained. 

1 Following are the affirmative considerations set forth by Taylor in connection 
with lathe tool design: 

The bar from which the tool is forged should be one and one-half times as deep as 
it is wide. 

The cutting edge and the nose should be set well over to one side in order to avoid 
the tendency under pressure to upset in the tool post. 

That shape should be given preference with which the largest amount of work can 
be done at the smallest combined cost of forging and grinding. 

Forging is much more expensive than grinding, therefore a tool should be designed 
so that it can be ground the greatest number of times with a single dressing and the 
smallest cost per grinding. 

The best method of dressing a tool is to turn its end up high above the body. 



262 



HIGH-SPEED STEEL 



Defects of Tool Holders. — The stock of a lathe (or similar) tool not 
only serves to support the cutting portion, but also to conduct away 
a considerable part of the heat generated in cutting. In order to do the 
first effectively the stock must, as has been pointed out, be strong 
enough to prevent springing and chatter. Holders for this reason, if 
used at all, should be made of chrome or other very tough steel. Also, 
if used, they ought to be so designed that the tool itself will fit snugly, 




Fig. 220. A type of composite tool, suited to scraping. 

or even tightly, into the slot provided, so that there will be close con- 
tact on all sides between tool and holder in order to allow the heat to 
be conducted freely from the one to the other. Under the very best 
conditions, in this respect, there is likely to be something still wanting; 
and this lack is emphasized by the fact that in all such -mechanical com- 
binations of tool and holder there is introduced one additional joint in 
the circle which includes tool, tool post and slides, lathe bed, head stock, 
spindle, chuck or dogs, and the work itself, and thus brings in an addi- 
tional element of negative force in high-speed cutting where especially 
rigidity is essential. 



FUNDAMENTAL CONSIDERATIONS IN THE DESIGN OF TOOLS 263 

Compound or Welded Tools. — The better practice seems to be to use a 
stock of chrome, nickel, or other tough steel with a nose or cutting end of 
high-speed steel either electrically or autogenously welded on (see Figs. 151 
and 152), or possibly joined by some other method of rendering the parts 
homogeneous, as described elsewhere. Tools so made can be forged to 
standard or special shapes and re-fettled as necessary. They have the 
requisite strength, avoid introducing additional holding devices with the 
consequent liability to movement, allow the heat to be conducted away 
from the cutting edge without interruption, and are in practically every 
respect equal to solid high-speed steel tools. The cost probably is a 
little higher than that of tools used in holders, but the advantages 




Fig. 221. Types of milling cutters best made from the solid stock. 

clearly outweigh any slight difference in this respect. Tools with 
cutting surfaces brazed to ordinary steel bodies or stocks have been in 
use for a number of years in planer and similar work (see Fig. 149), 
and to some extent also in turning operations. Where no forging, or but 
a .slight amount, is required, these are very satisfactory. The method 
does not commend itself in connection with tools of the Taylor standard 
shapes, or others except those of simple form. 

Composite Rotary Tools. — In milling cutters and other rotating tools 
of large diameters there is opportunity for economizing in the use of 
high-speed steel by the use of this material for the cutter parts only, 
the body of the tool being in a large proportion of the cases quite as well 
made of cheaper material. The smaller cutters, say those below 4 or 
5 inches diameter, and most irregular shapes, are usually made solid 
for the obvious reason that they cannot be conveniently or economically 
made with inserted blades, especially if held by mechanical means. A 
certain amount of room is required, which in small diameter tools is not 
available even if the number of cutters be reduced considerably below 
the customary; and the necessary smallness of the securing parts usually 



264 



HIGH-SPEED STEEL 



tends to insecurity in the holding device. The objection to tool-holder 
lathe tools touching the lack of heat conductivity, does not hold in respect 
of milling and similar cutters. The cutting edges are at work for a 




Fig. 222. Something unusual in the way of large milling cutters, 9x2 inches. Made from the solid because 
composite cutters would not stand up to the work required. The peculiar form of the teeth pre- 
vents dragging and gives free cutting angles all round. 




Fig. 223. An interesting composite milling cutter. So designed that the blades are easily removed 
and ground simultaneously by the aid of a grinding fixture. Courtesy of Mr. William G. Thumm. 

relatively short time during each revolution, and are exposed for the 
remainder of the time to the cooling action of the air. On this account 
they do not tend to become heated during a long run. In all the larger 
sizes, therefore, where it is convenient and feasible to secure the cutting 
blades mechanically, this is usually the preferable method. This the 
more because of the difficulties inherent in hardening not only these, 



FUNDAMENTAL CONSIDERATIONS IN THE DESIGN OF TOOLS 265 

but most other large tools of intricate form. All such are to a greater 
or less extent susceptible to cracking, which though it may be reduced 
to a minimum by use of the barium hardening method or extreme care 
with other methods, still may possibly occur, the cracks, when they do 
occur, often not becoming manifest until the tool has been put at work. 




Fig. 224. Type of inserted-blade milling cutter. 

This composite method permits the use of a tool body, with properly 
made recesses for blades and means for securing them, once made, to 
be used with an indefinite number of cutter sets, in this. way reducing 
the actual tool cost on any given job very materially below what it would 
be if the ordinary solid carbon cutter were used. 




Fig. 225. A cold saw (Taylor-Newbold) with inserted teeth held in place by soft metal. 

Methods of Securing Cutter Blades. — The methods of securing cutter 
blades are not only divers, but of various degrees of excellence. Brazed 
cutters have been used, and in a few instances also welded ones. These 



266 



HIGH-SPEED STEEL 



methods produce the strongest tools; but they have the disadvantage 
of making the body, with its expensively cut recesses, usable but the 
once. Holding the blades in place by means of screws is, in general, to 
be avoided because of the well-known tendency of threaded parts to 
work loose and sometimes to require replacing with new and over-sized 
ones. Screws in some cases are used for the purpose of expanding the 
peripheral sections of a cutter in such a way as to grip the blades between ; 
and this is an excellent way. Expansion dowels are similarly used, as 




Fig. 226. Tooth of Taylor-Newbold saw broken. The tool or holder will break before 
the soft metal bedding the tool in the holder is materially damaged. 

also are wedges. In the latter case, however, there is more or less diffi-- 
culty in extracting the blades when worn out — a matter of some impor- 
tance. For many uses it is sufficient to make the blades of such form 
and size that they are merely pressed into place with a forced fit. The 
method of imbedding the cutter blades in soft metal, hereafter described, 
also has advantages. 

Helical Milling Cutters. — For side facing mills and others needing but a 
narrow peripheral cutting face, where the blades are of little length, they 
are sometimes straight, but are most often set at an angle so as to secure 
the advantage of a partially shearing cut. The same thing has been tried 
with long cutters, but in this case it is impossible to make a satisfactory 
mill without the use of helical blades. The slope and lip angle of a mill- 
ing cutter blade obviously should be uniform, or nearly so, throughout 
its length. In very short straight blades this will be the case nearly 
enough for practical purposes, but where the cutters are long, unless bent to 
a helical form, if set with the front face at an angle with the axis, the slope 
and angle are uniform at. no two points along the cutting edge but are 
modified to such an extent that the length of blades so set is thereby very 



FUNDAMENTAL CONSIDERATIONS IN THE DESIGN OF TOOLS 267 



limited, and mills so made are liable to excessive vibration and chatter. 
In the case of helical cutting edges the front slope and lip angle can be 
maintained uniform throughout their 
length. Heretofore, however, it has 
been rather difficult to manufacture a 
cutter with blades of this form satis- 
factorily and effectively secured. This 
is now done by milling (or sometimes 
planing) key or pocket shaped helical 
slots, relatively large as compared with 
the blades, and anchoring the blades 
to the holder or tool body by filling 
the vacant space with some soft alloy 
like type metal and compressing it to insure a perfect imbedment of the 
blades. Anomalous as it may seem, tests have proved that blades, or 




Fig. 227. Development of front slope from 
to a positive front slope in the case of a 
straight inserted cutter blade set at an angle 
to the axial plane. Courtesy Tabor Mfg. 
Company. 




Fig. 228. How the front slope varies from the maximum at R 1 to the minimum at R* in a straight blade 
set at an angle of 20 degrees to an axial plane, while it remains constant throughout the length of 
the helically curved blade set at the same angle. The condition arising in the former case limits the 
possible length of the blade. Courtesy of Tabor Mfg. Company. 

even holder, will usually break before the anchorage is materially dis- 
turbed by stresses upon the cutter blades. Blades so held are removed 
without trouble when in need of replacing. A well-known cold saw, it 
may be said in passing, has its teeth secured by a similar method. 

Renewing Inserted Cutters. — This matter of renewals is dependent very 
largely upon the relative amount of cutter blade which can be ground 
away, and the method of grinding — that is, whether face or back grind- 
ing. The latter is by far the better, a very small amount of metal re- 
moved serving to sharpen the tool where a heavy face grinding would 
be required to accomplish the same result. The life of a set of cutter 
blades of this sort, then, depends upon the number of grindings that can 
be given it, which is to say, upon the overhang or distance the blades 



268 



HIGH-SPEED STEEL 



project from the housing. This distance will naturally be governed by 
the work to be done, that is, by the stresses to be provided against. 
Under ordinary conditions a projection of one and one-half times the 
thickness of the blade is not too much. Cutters not helical in form may 
not permit quite so much projection. 



^-CLEARANCE 



LIP ANGLE 




Fig. 229. Unique method of holding inserted cutter blades in position by imbedment in soft metal. The 
front slope is given to the blades by curving the face. Courtesy Tabor Mfg. Company. 

Maximum Number of Blades. — Where metal is removed as rapidly 
as it should be with milling cutters of the high-speed type, the question 
arises as to clearance for the chips as they are cut away. The pitch 
ordinarily used in carbon steel milling cutters is insufficient, especially 
in cutting soft metals. Furthermore, the mechanical fastening of the 
blades also limits their number. Just what should be the number of 
cutting edges does not seem to have yet been scientifically determined. 
This much is known, however, that the best results are not obtained 
where the number of cutters is large. Coarse feeds are coming more and 
more to be the rule in all except fine finish milling; and for such work 
evidently the number of blades will be governed to a large extent (in 
connection with the considerations already mentioned) by the load it 
will be practicable for each blade to carry; for the abutments for the 
several blades, taken together with the thickness of the blades them- 



FUNDAMENTAL CONSIDERATIONS IN THE DESIGN OF TOOLS 269 



selves, must be sufficient to withstand the 
probable stresses imposed. For most classes 
of such cutting operations the number Of blades 
will vary from about one for each inch on the 
periphery in small diameters, say 4-inch, to 
about one for each 1£ inch of periphery when 
the diameter is as great as 10 inches. This 
would give about 14 blades for a 4-inch 
nominal diameter, 16 for a 6-inch, 18 for an 
8-inch, and 20 for a 10-inch cutter. The arbor 
hole should never exceed one-half the nominal 
diameter. In the case of side and face mills, 
where the chips are not confined, a greater 
number of cutters is allowable if considera- 
tions of strength and proper securing permit. 
Evidently a solid cutter can have a greater 
number of teeth than one with inserted 
blades. Such an increased number, however, 
is not at all necessary, for the work done with 
one of coarser pitch will be quite as good as 
that with the finer. Furthermore, the cost is 
in the neighborhood of a third less. Usually 
also the life of a coarse pitched cutter will be 
considerably, not infrequently several times, 
greater than that of one with the greater 
number of cutting edges. 

Rake for Soft Metal Cutting.— Milling cut- 
ters (and most other tools as well) intended to 
work on aluminum, and perhaps on other soft 




Fig. 230. A Tabor inserted blade 
milling cutter of some size. 
Scarcely feasible to make it 
solid. Blades secured by im- 
bedment in type metal. 



metals also, require more rake than those cut- 
ting iron and steel, in which latter case 5 de- 
grees is about right. An angle of 45 degrees 
from the vertical gives a beautiful clean finish 
when paraffine is used as a lubricant. The 
removed material does not under these con- 
ditions pile up on the face of the cutter, rough- 
ing its surface and preventing the cutting of a 
clean chip as often happens otherwise. The 

Fig. 231. High-speed milling cutters . ,. ,. , ,, , , T 

should have about 5 degrees of pitch or distance apart ot the cutters also IS 

slope to the cutting lips. ' .. . ,, . , , , a • -\ . 

necessarily greater, three teeth to a 4-incn cut- 
ter being amply sufficient, while a cutter as large as 10 inches requires 
but 6 teeth. More than this number is unnecessary to secure a good 
finish, and would be in the way of chips, preventing their clearing out 
properly. 




270 



HIGH-SPEED STEEL 



Nicking the Cutting Edges. — The question as to whether the cutting 
edges of long mills should be nicked or not is still open, though it would 
seem that if the cutters were designed with a front slope such as. to 
bring down the chip pressure there would be no occasion for breaking 
up the chip. This front slope is an important factor in the efficiency 
of milling cutters. 

Interlocking Mills. — Wide face cutters, when solid, are preferably 
made in interlocking sections, as also are those used for producing 




Fig. 232. The gang milling cutter, built in sections in order to simplify problems of manufacture, 
hardening, grinding and maintenance. 

finished surfaces with a variety of curves, slopes, or angles. In the 
latter case gangs are used, a separate cutter for each surface or curve, 
usually. The difficulty of properly hardening a single cutter of extreme 
length or intricate form would be sufficient reason. A further one is 
that in case of damage to a portion of such a cutter, if made in sections 
the damaged part can be replaced without the expense involved in the 
making of a complete new cutter. 

The Case of Rose Reamers. — Rose and similar reamers have several 
points in common with milling cutters, yet in certain respects are in a 
class by themselves. Those used in a vertical position, for enlarging 
and truing cored holes, discharge their cuttings freely; but those working 



FUNDAMENTAL CONSIDERATIONS IN THE DESIGN OF TOOLS 271 



in a horizontal position often present a difficulty in this respect, and 
require greater clearance in order to avoid clogging and other troubles. 
As in milling cutters, in order to secure a sufficient clearance, and at the 
same time sufficient strength in the backing or abutments supporting 
the cutting edges, the number of the latter is reduced as much as a third, 
frequently, below the customary. 

Composite Reamers. — Small sizes, say up to H inch, are preferably 
made solid, and above that diameter with inserted blades, though some as 
small as | inch are made composite — and adjustable at that. The manner 
of insertion may be either mechanical or intimate, as with milling cutters, 




Fig. 233. Matthews expanding shell core trill or reamer. Expansibility secured 
through slotted shell in combination with an expansion bolt. 

though in the former case the mode of holding is essentially different. 
If intimately attached, so as to make a practically homogeneous tool, 
either by brazing or by welding, the effect is that of a solid tool which 
may be ground off without reference to saving the core or body. This 
is convenient, especially when the operator is required to grind his own 
tools — as he should not be. By the use of suitable collars and other 
well-known devices the blades may be secured at both ends, and when 
ground away until no longer serviceable are quickly replaced by another 
set. Likewise there are reamers whose blades are forced with a drive 
fit into the grooves cut in the body of the tool; and still others with blades 
wedged in or secured by screw devices. Almost any of these are efficient 
in light or moderately heavy work, particularly if used as floating reamers 
for sizing rather than for boring. When, however, extra heavy service 
is required there is some difficulty in securing the blades mechanically 
so that they will stand up to the work. It is desirable in this case that 
the blades be brazed or welded — and to cores strong enough not to 
twist off at the shank. 

Material for Stem or Body. — To afford the requisite strength in tools 
of the last mentioned kind, the body and shank are best made of a 



272 



HIGH-SPEED STEEL 



tough chrome or similar steel. Machinery, and even tool steel shanks, 
not infrequently twist off under the heavy stresses imposed by severe 
duty. For ordinary work under customary conditions the bodies are 
strong enough if made of machinery, or at best of tool steel. Occasion- 
ally it may be desirable to make them in the form of steel castings, though 
usually the ordinary method will be followed. Bronze metal bodies, 
with the slots for the blades milled in the customary manner, also are 
in successful use. The blades in this case are brazed into the recesses. 
Cast or malleable iron bodies are to be avoided. 

Clearance and Relief in Reamers. — High-speed reamers especially, 
and perhaps more than the slower carbon steel sort, require a sufficient 
and proper clearance or relief. Too much will result in chatter, while 
too little will lead to binding in the hole and consequently to short 
life. Flat relief, that is, a flat land behind the cutting edge, or front 
face of the flute, is not nearly so good as a curvilinear, the so-called 
eccentric or radical, which not only gives better support to the face of 
the flute but also helps to steady the tool and produces a better hole. 

Expansion or Adjustable Reamers. — The work of a rose reamer is 
essentially different from that of either a milling cutter or of a drill, 
since the former removes but a relatively thin skin of material from the 




Fig. 234. Smith adjustable reamer assembled, and parts of same. 



inside of a hole already existing; and unlike either, it takes this off not 
with a broad cutting edge, but with a small corner of the cutting lip at 
the periphery of the tool. In consequence nearly the whole wear comes 
just at that point in the reamer which gives the size to the hole. And 
since the only way in which work of this character can be kept within 



FUNDAMENTAL CONSIDERATIONS IN THE DESIGN OF TOOLS 273 

the requisite limits of precision is to keep the tool also within those limits, 
it is necessary to keep such reamers well sharpened by frequent grind- 
ings, or to provide for taking up this wear by some method of expansion 
which will again give the required diameter. In most cases where the 
nature of the work is such as to permit the use of tools of that type, the 
expansion reamers are preferred. The simplest form of such a tool, 
perhaps, is that in which the blades are welded or brazed to a slotted 
shell provided with a taper plug and take-up screw. In. another well- 
known tool, with removable blades, the expansion is accomplished by 
rotating a locking cam bolt with cams corresponding to the blades. 

Twist Drills. — In fluted twist drills there has been little change from 
the standard form previously in use, though it is desirable that the lead 
of the flutes be given some advance over the customary one of about seven 
times the diameter. The smoothness of finish somewhat affects the possible 
speed and therefore the efficiency of drills. Provision should therefore 




Fig. 235. Chard spindle drill. 

be made for a finish approximating a polish. The one especial feature 
wherein the high-speed drill can well differ from the ordinary is in the 
thickness of the web. In order to give the greatest possible degree of 
stiffness and strength where most required, it is a desirable, but by no 
means an universal practice, to increase the thickness of the web grad- 
ually toward the shank. It is important that the web, especially when 
the drill has become somewhat shortened, should in grinding be thinned 
at the point in order to minimize the tendency to split which sometimes 
manifests itself at the high pressures required to feed these tools into the 
work. Likewise it is not only important, but essential, to provide for 
the grinding of a proper clearance to meet the requirements of the feed 
intended to be used, ana, as explained elsewhere, for so varying the 
clearance angle from center to periphery as to allow the drill to feed 
properly into the work at all points along the cutting edge. 

Twisted Drills. — For a time at least one maker of high-speed steel 
rolled sections of such shape that when suitably twisted and provided 
with a shank, a fluted twist drill was produced which required only to 
be finished and ground, the cost being surprisingly small. This was, 
in a sense, a reversion to the original method of making drills of this 
type. The maker after a time ceased rolling the drill stock section; but 



274 HIGH-SPEED STEEL 

others have since then taken up the idea and now several forms of drills 
are manufactured in this way, ranging from those twisted from flat 
stock to others rather closely approximating the standard milled fluted 
drill. There is no difficulty in producing a shank suited to any require- 
ments, from the regular taper to special forms adapted to use in con- 
nection with special collets or chucks. In one style the lead of the 
twist is considerably increased at the shank end so as to form a good 
bearing, which when ground not only fits the standard taper socket, but 




Fig. 236. Twisted drill made from a flat bar of stock throughout its entire length. 
Shank ground to standard taper. 

by reason of the tendency to untwist under the stress of work, it actually 
grips the taper seat more firmly than a solid shank drill does. Other 
styles have hot pressed or slightly forged shanks, flat or flat-taper, as the 
case may be. 

Economy in Twisted Drills. — The manufacture of drills of this type 
obviously is a much simpler and cheaper matter than that of the ordinal 
fluted drills. The amount of metal required is only about one-third as 
much by weight, which of itself is a matter of consequence; and the 
twenty odd operations involved in the manufacture of ordinary drills 
is reduced to a small fraction of that number. No expensive or elaborate 
special outfit is required to make them, and it is therefore possible to 
produce drills of this type in many shops otherwise not equipped for 
drill making. In addition to all these things, it would appear that 
drills thus twisted are stronger than those milled from the solid cylin- 
drical stock and that tangs very rarely twist off or stems break under 
the strains of their work. Obviously the grinding and finishing must 
be as carefully done as in the case of the ordinary type. 

As to Other Tools. — There does not seem to be any reason for depar- 
ture from traditional lines in the design of wood working and of metal 
working tools other than those used for rapid cutting, except in so far as 
it is desirable to make all these tools so far as permissible on the com- 
posite or built-up plan. Small dies, punches, shears, and the like tools 
are preferably solid; but large sizes are just as well, or better, built up 
in such a way that the parts subjected to wear may be renewed from 
time to time as required. 



CHAPTER XVIII. 

THE NEW MACHINE REQUIREMENTS. 

Limited Use of High-Speed Tools.— The revolution in machine shop 
practice, so enthusiastically predicted for some time, unquestionably is 
arriving; but, it seems, rather more slowly than might have been expected; 
and it is as yet manifest in spots only, so to speak. Considering the 
very great advantages obtainable by the extensive and intelligent use of 
high-speed steel tools, it is surprising, not to say disappointing, from 
the efficiency point of view, that they are as yet used so little and so 
ineffectively in general manufacturing. In such plants as have for 
their principal product heavy forgings or machinery, or other products 




Fig. 237. An extraordinarily large and heavy lathe in its day. Built about 1856 by the Phcenix Iron 
Works, Hartford. Compare the weight and build of this machine with a modern high-speed lathe 
of about the same swing, as seen in Fig. 238. 

comparable to them, the new steels have a large and not infrequently 
exclusive place. In a relatively few shops turning out products of a 
different character, say such as would be typified by agricultural ma- 
chinery, sewing machines, and watches, advantage is also taken of the new 
steels and their high efficiency. In the average factory, however, the 
extent to which they are used is astonishingly small. There are indeed 
places where high-speed steel seems never to have been heard of, or where 
the management is so ultraconservative as apparently to deserve being 
under suspicion of inefficiency and to need reminding of the adage which 
says something about penny-wise and pound-foolish. 

275 



276 



HIGH-SPEED STEEL 



There are of course many considerations affecting the use of high- 
speed steels, and these are discussed in another plage. One of the most 
important relates to the nature and effectiveness of the machine tool 
equipment; and it is this which particularly concerns us at present. 

Incapacity of Old Equipment. — It scarcely needs mentioning that ma- 
chine tools designed under the old regime, to meet the requirements and 
reach up to the limitations of the old tools, are utterly incapable of using 
efficiently the new tools, with their doubled, trebled, and even quadrupled 
powers. It may be necessary or expedient to use such equipment even 
in connection with high-speed tools, as pointed out in another place; 




Fig. 238. Example of powerful and massive lathe especially adapted to use high-speed steel tools. 
Double head, one of which has traverse. Feed and headstock traverse both secured through an aux- 
iliary motor seen at the farther end of the machine. 80-inch Niles driving wheel lathe. 

but in the acquisition of new equipment there certainly should be no 
hesitation in selecting that which will measure up to the full powers of 
the new tools, and then to use those tools at their maximum efficiency. 

Sufficiency of the New Types. — During the first years of high-speed 
steels, machine tools fulfilling the new requirements were not often to 
be found. Builders were cautious in the matter of new design and the 
expense of putting out new types of machines — though it may be sup- 
posed that they were no more conservative in this respect than the market 
demands made prudent. The early attempts at adaptation to the new 
standards were mainly in the way of modifications of existing designs. 
There was some increase perhaps in the weight of beds and frames, and 
a disposition to displace the narrow, many-stepped cone pulleys of the 
ancient yesterday with others having faces somewhat broader. But 
there was much hesitation in the bringing out of machines newly de- 
signed, with the problems presented by the new tools as the basis of 



THE NEW MACHINE REQUIREMENTS 



277 



many departures from tradition in the working out of general form as 
well as of details. At the present time, however, it is possible to obtain 
machine tools of almost any type which will measure up to the maximum 
requirements of the new tools, and which possibly surpass them in some 
cases. This being so, it is pertinent to inquire as to the elements which 
should be considered in the selection of machines under the new regime. 




Fig. 239. A drilling machine that fulfills the most exacting requirements for a high-speed, 
high-power tool. Made by Baker Bros., Toledo, Ohio. 

Producing Repetitive Work. — Before attempting to indicate some of 
the most important of these, it is pertinent to point out that the ques- 
tion of machine tools may well be looked at from two very different view 
points by the two classes of machine users to whom it might be supposed 
to be of interest. The requirements of the shop doing little but repeti- 
tive work, the reduplication of pieces in great numbers, pieces which 
need to be " good enough " merely (or even which need to be of extreme 



278 



HIGH-SPEED STEEL 



accuracy, though possibly to a somewhat less degree), will be much 
simpler and perhaps less exacting than those of what might be called 
the general job shop, where a given machine may be called upon to per- 
form a great diversity of operations upon a large variety of different 
kinds of pieces. In the former the use of the jig and similar devices 
to hold the piece operated upon and to guide the tool to insure accuracy, 
makes possible in most cases the satisfactory use of machines fulfilling 
two essential requirements: ample powering and sufficient rigidity or 
strength. Even the latter is essential not so much for reasons of accuracy 
as to insure longer life to the tool through the elimination of vibration. 




Fig. 240. An interesting effort to meet modern requirements in repetitive production. 
The Foster ring-turret lathe. 



The small range of work generally done upon a given machine, under the 
conditions named, not only eliminates the need for a great variety of 
speed changes (once the proper speed for the jobs to be done upon it 
has been determined), but actually makes such a variety a needless 
source of expense and something of a nuisance besides. The tendency, in 
shops having a very large output at any rate, is toward the highly spe- 
cialized machine, designed specifically for the performance of a single 
operation or a very few specific operations, on particular parts. For the 
single operation machine but a single speed and but few adjustments 
are required; while for the other, the speed changes may well be closely 
restricted. 



THE NEW MACHINE REQUIREMENTS 



279 



The Case of Engineering Works. — Manifestly the shop turning out a 
limited number of pieces of a kind and doing a large variety of work, 
whether it be the tool room of a big factory, the general manufacturing 
shop, or the small jobbing shop, requires a different class of machines. 
Since jigs and rigs are of necessity but little used, precision must be 
obtained through accuracy in the operation of the machine. For this 
reason the machines must meet the additional requirements of extreme 
rigidity, considerable range of adjustability, and likewise large range of 
speed variation. Whatever the type of machine, the considerations 
here pointed out apply with more or less force to all of them. 

Solidity and Rigidity — How Secured. — Much has been said, and not 
a little written, about the so-called " anvil " as opposed to the " fiddle " 
principle in machine design; and it was pretty well established even 
before the advent of the new tools that solidity, or rather rigidity, is a 
prime essential in machines for metal working. Solidity and rigidity 




The Engineering Magaz 



Fig. 241. How the disposition of material in structural forms affects strength and effectiveness in resist- 
ing strains. A and B are three and four sided prisms. C is in the form of two girders connected at 
intervals by girts. B has 10 times the torsional resistance of A, and from 6 to 13 times that of C, 
the ratio depending upon the strength and frequency of the girts in C. 



are by no means the same thing. Mass of course does involve inertia, 
and likewise rigidity. On the other hand it is possible to secure com- 
parative freedom from vibration without the heavy massing of material 
often found, if the material be properly distributed. It is well known, 
for instance, that the hollow cylindrical form of construction is very 
much stronger in every way than the solid, utilizing the same amount of 
material; and this fact is made use of in a great variety of ways — - 
nearly every way, one might have said until very recently, except the 
construction of machine tools. The hollow prism form also has great 
advantage over the solid, considering the amount of material involved. 
It has been shown experimentally that a hollow four-sided box of this 
rectangular prism shape (Fig. 241) is more than six times as rigid 
with respect to twisting strains as the same amount of material in side 
plates with cross girts of the customary proportions. Even the very 
best possible distribution of material in this form (beams and girts) 
does not reduce the disproportion more than half. Consequently the 
very best lathe bed designed on conventional lines can have a strength 



280 



HIGH-SPEED STEEL 



ranging only from possibly a fourth (making a very liberal allowance) to 
an eighth of the rigidity it might have if the material were distributed 
in the box form. Now the chief business of not only lathe beds, but of the 
frames of nearly all machines designed for rotating the work or the cutting 
tool, is to resist such twisting strains; and principles of rational design 
should indicate the advantage of this simple mode of reducing the 
weight of metal required, or rather of securing the maximum of strength 
and rigidity from the metal used. The nearer, therefore, a lathe bed 




Fig. 242. A heavily girted lathe bed. 



approaches this form, the greater its efficiency. The same thing holds 
true of such parts as the cross rails of planers, multiple mills, and the 
like machines. These most frequently have been made trough shaped, 
with a section resembling a box of three sides rather than four — a form 
lacking in resistance to torsional strains, and only about a tenth as strong 
otherwise as if one-third of the metal were distributed in the form of 
a fourth side. 

Weight Essential. — It should not be inferred that lightness is in any 
wise desirable in machines designed for using high-speed tools. The 
heavier the frame, that is to say the greater the solidity, the better 
the absorption of vibration such as inevitably occurs in heavy or rapid 
cutting; and the better this is absorbed, the greater the efficiency at the 
cutting edge. The point is that there shall be ample weight, and that 
this weight shall be distributed for greatest effectiveness in resisting the 
kind of strains to which the particular machine is to be subjected. And 
this applies no more to lathe than to milling machines, planers, and the 
rest of the tribe of machine tools. 



THE NEW MACHINE REQUIREMENTS 281 

Lathe Heads and Others. — Next in importance to the bed, frame, 
or body of a machine, is the driving or cutting head. Obviously it ought 
to be in strict proportion to the rest of the machine. It needs strength and 




Fig. 243. "Lo-Swing" lathe (rear view) of the Fitchburg Machine Works. Unique design of bed — and 

indeed of machine throughout. 

rigidity just as much as the body does — but no more. The practice 
of putting abnormally large heads upon machines otherwise of moderate 
resisting power, as was done to a considerable extent at first, by no 
means makes a high-speed machine of an ordinary one. There is no 
more reason for putting a tremendous head upon an ordinary machine, 
producing a megacephalous monstrosity ("hydrocephalous," somebody 
has facetiously remarked, possibly in reference to the designers rather 
than to such machines themselves), than there would be in using an 
immense tool without a suitable" support. The head must have solidity, 
however, and must be large enough to allow for the increased size of 
bearings necessary for the higher speeds and heavier driving; and in case 
gears take the place of pulleys, to accommodate the change gears requisite 
to the type of machine. It is important that the attachment of the head 
to the bed or body be such as to insure the greatest possible stability; 
and this precludes, except in machines of special type intended for special 
service, any adjustability of these parts. A satisfactory attachment 
is of course possible if the contiguous bases are sufficiently large, well 
fitted, and securely bolted. No such attachment, however, can be as 
rigid as if the parts were made in one solid piece; and some of the best 



282 



HIGH-SPEED STEEL 



types of machines now have frame or bed and head cast in a single piece. 
This naturally involves larger and more complicated castings, and it 




Fig. 245. Section through Darling & Sellers lathe bed and carriage. 

would be interesting to learn if the same results might not be obtained 
by casting in two pieces (or more) as heretofore and making them homo- 



THE NEW MACHINE REQUIREMENTS 



283. 



geneous by one of the several processes of welding now successfully 
employed in other ways. There seems to be no reason why this should 
not be the solution to the rather vexing problem of how to secure the 
largest amount of rigidity with moderate cost of manufacture. 




Fig. 246. Warner & Swasey hexagon turret lathe. Head and bed cast in one piece; direct connected 

motor drive; flat turret carriage. 



Proportions of Bearings. — Properly proportioned bearings are much 
more important in the new machines than formerly even. Not only 
is the highly increased speed to be considered, but also the very largely 
increased pressures. To meet these conditions the bearing surfaces 
must be large, and of material best calculated to resist wear and to 
avoid friction. Considerations of space as well as of rigidity make it 
preferable that the augmentation of bearing surface should result from 
increased diameter rather than greater length. This permits also the 
use of hollow spindles, which again tend to greater strength and rigidity 
and permit the better use of gears in the driving mechanism. 

Lubricating Devices. — In machines of the types heretofore standard 
the matter of lubricating bearings (and gears, when used) has not been 
particularly troublesome. Under the new conditions it is less simple. 
The tremendously increased pressures and friction make it necessary 
in many, if not in most cases, to provide some means to insure free and 
certain lubrication. This involves often the designing of special devices. 
An ingenious example is that used on one high-speed lathe, Fig. 250, 
wherein the bearing is surrounded by an oil-filled well. Oil is con- 
tinuously dipped and carried in sufficient quantity to the highest part 
of the spindle and is conveyed to all parts of the bearing through the 



284 



HIGH-SPEED STEEL 



customary oil grooves. A glass tube inserted in front and properly- 
protected serves as a level indicator. In another instance (Fig. 247) 
the gears are about half immersed in oil contained in the pan formed by 
the gear case. Of course both are well covered. In the case of certain 




Fig. 247. 



Headstock of hartness fiat turret lathe. Cover removed to show gears and oil pan. 
The gears run in oil. 



very heavy duty machines it has been found desirable to force oil into 
the bearings by small force pumps. 

Secondary or Tail Stocks. — In machines requiring a secondary stock 
for the support of the work turning; on centers, as in the case of the 




If^CHINCkY NY 



Fig. 248. Making a lathe center with a high-speed steel cone. The welded spindle with bur, and same 
completed. Courtesy Thomson Electric Welding Company. 

engine lathe, this tail stock must be designed with reference to heavy 
service; that is, with sufficient base, heavy weight, and security in 
fastening to be in balance with the head stock. It is desirable that 



THE NEW MACHINE REQUIREMENTS 



285 



there be some provision for positively bracing it against the bed. The 
tail spindle, and indeed all centers subjected to much wear, should by 
all means be of high-speed steel. It - is not necessarily solid, however, 
for it is sufficient if a high-speed steel center end be welded or otherwise 
securely attached to a tool steel shank. In large machines it is desira- 
ble that the tail stock or secondary head be moved as required by an 
auxiliary motor. 

Tool-Holding Requirements. — Much attention has heretofore been 
given to securing a great variety of adjustments in the mechanisms 
employed to hold the tool and to bring it to its work. The result is 
that compound rests have not infrequently been " fearfully and wonder- 
fully made," in order to give a maximum of adjustment and movement. 




Fig. 249. Method of attaching back rest and carriage in "Lo-Swing" lathe. 

While of course refinement of adjustment and facility in bringing tool 
and work together are desirable in high-speed cutting also, it is still 
more desirable that they be brought together as rigidly as possible. 
Every joint means a reduction in rigidity; and in work requiring freedom 
from this to the extent necessary when working high-speed tools at a 
high efficiency, evidently the fewer slides and other adjustments, the 
better calculated is the machine to do its work with the minimum of 
vibration. Absolute freedom from vibration is not possible in a cutting 
machine. The absence of chattering or of tremors capable of being 
sensed does not necessarily indicate that they are not present to some 
extent. At the best they can but be minimized. The tool-holding 
device and its adjuncts must compare, in rigidity and strength, with the 
rest of the machine, and require wide bases combined with the least 
possible altitude. It is not at all essential that the shank of a tool shall 



286 HIGH-SPEED STEEL 

be horizontal, in the case of a lathe, for example; so that there need be 
no difficulty in considerably lowering the position of the tool with refer- 
ence to the working center. The same consideration holds in the case 
of all other machines. Thus that milling machine is best adapted to 
high-speed work (other things equal) which has short arms and holds 
the tools closest to the main frame; and in planing, the least torsional 
strains are thrown upon the cross rail when it is possible to cut with the 
tool point very nearly in front of the rail rather than below it. It may 
be added in this connection that the sharp angle or unusual rake per- 
mitted in the case of one well-known special lathe is in large measure 
due to this practical elimination of torsion in the bed, the reduction 
of slide movements to the irreducible minimum, and the lowering of the 
tool to the greatest possible extent. Reciprocally the tool reduces the 
pressures and consequent strains, and there is insured better work 
with lower power consumption than often is the case. 

Increased Power Required, not Waste. — The powering of the new 
machines, providing them with pulling power adequate to the needs of 
the new situation, has developed to a satisfactory state, though not 
infrequently mere modifications of former types have been attempted 
in the effort to remodel old designs — generally with small success. 
It is understood, of course, that increasing the amount of cut, in metal 
cutting, increases the power consumed; and also that increasing the 
cutting speed does the same. The increment, however, is by no means 
proportional to the greater amount of metal removed, and it by no 
means follows that because a machine consumes power rapidly, energy 
is going to waste. It is demonstrable beyond question that an efficient, 
high-powered and high-speed machine using a tool of the new type has 
an efficiency very much greater than the old machines even if the 
absorption of power alone be considered in relation to the amount of 
work done. In other words, on the basis of time consumed and metal 
removed, a strictly modern machine uses considerably less energy per 
unit than do the former standard machines. 

The Belt-Driven Machine. — Of course extremely heavy cutting is 
necessarily confined, in large measure, to shops doing a particular class 
of work (comparable to armor plate and gun making operations, say), 
and have a relatively small place in the ordinary run of general manu- 
facturing. Nevertheless, the effective use of high-speed steel in this 
very kind of general manufacturing requires high-powered machines 
also. Obviously heavy driving power is out of the question in con- 
nection with the multiple cone pulley, even if nothing be taken into 
account other than considerations of space and the danger connected 
with the shifting of rapidly running belts. If a belt drive is necessary, 
that machine should be best suited to the new requirements which has 
but few steps in the driving cone pulley (say not to exceed three), or 



THE NEW MACHINE REQUIREMENTS 



287 



which has no step cones at all. In the latter case all variations in speed 
are of course obtained through a variable speed countershaft, a gear 
box, or the two in combination, the number of changes required being 
determined by the nature and variety of the work for which the machine 
is desired. In general manufacturing, as already intimated, a great 
variety of speeds and feeds is not only unnecessary but often a source 




Fig. 250. Lodge & Shipley single-face pulley drive in connection with gear box. Cover and bearing caps 
removed to show positive lubricating device. 

of needless expense and annoyance. Wherever possible, it is better to 
have the machine drive suited to a small range closely accorded with 
the requirements of its special work. 

Few Speed Changes Necessary. — The gear box in connection with a 
variable speed motor offers a combination with which are obtainable 
a maximum number of speeds in cases where the work of a machine is 
much diversified. Even in such instances the number of different 
speeds really necessary need not be very great. The new tools lend 
themselves admirably to wide latitudes in respect of speeds, and feeds 
also; so that in spite of an evident tendency in some directions to require 
more rather than fewer changes, it would seem the better plan in general 
to get along with the less number, except under special circumstances. 

Amount of Power Absorbed. — The amount of power consumed by 
machines under former conditions has been very generally overestimated 
because, among other reasons, the proportion absorbed by line and 



288 



HIGH-SPEED STEEL 



countershafting and other transmission devices has been underesti- 
mated. Except in case of very powerful machines the energy absorbed 
per unit, while cutting, rarely exceeded one horse-power. The newer 
machine tools of similar capacity require rarely less than three or four 
horse-power, and not infrequently several times as much. A 20-inch 
swing lathe, to take a concrete example, running at high-speed and 
taking a heavy cut, has on occasion absorbed a maximum of 30 horse- 
power, though its average consumption is less than 10 horse-power, 
and the minimum a good deal less than that. In turning operations, 
under favorable conditions, the power absorbed per pound-hour of 
metal removed varies from 0.03 to 0.07 horse-power, over and above 
that required to drive the machine itself. This is measurably less than 
under former conditions, where the consumption has been close to 0.05 
or 0.06 horse-power and upwards. 

Belts for Auxiliary Drives. — Using up power so rapidly, pulling loads as 
heavy as are thus required at the high speeds conditioning the work, 





1 


■ 


V ■ v 


T% 


[ 






■PI ^PJ 1 "V_ A 




gggfw • 




"^B 



Fig. 251. A heavy milling machine with auxiliary motors for movements other than the main drive. 



means practically the elimination of belt drives for the auxiliary move- 
ments of a machine, and the modification of the main drive also, as 
above pointed out, with the tendency apparently toward a main drive 
pulley, where this is used at all, of but one belt face, and that driven 



THE NEW MACHINE REQUIREMENTS 289 

whenever possible by a silent chain rather than by a belt. The speed 
changes and the auxiliary drives, therefore, are through gears; not only 
in the main drive, but in the feeding and other movements wherever these 
are necessary. The gears are put under such stresses that the ordinary ones 
are quite unsafe, and only steel or bronze is permissible as a material in 
view of the limitations necessarily imposed as to size. Steel rimmed 
gears also are satisfactory in large sizes. Of course steel gears are 
positive — too positive for the safety of the machine, it is sometimes 
urged; but shearing pins or other safety relief devices obviate any possible 
objection on this score. It is important to bear in mind that the feed- 
ing stress may under abnormal conditions (as of a very dull tool, for 
example) quite equal the driving stress; and it is therefore essential that 
the feed mechanism be, if not just as powerful as the drive, certainly 
adequate to the probable exigencies to be met in the operation of the 
machine, and therefore much stronger than usually found under former 
conditions. It is desirable also that all high-speed machines be pro- 
vided with good braking devices for quickly stopping should occasion 
require. 

Relation of Powering to Capacity. — It seems to have been a pretty 
generally recognized principle of machine design, prior to the advent of 
the high-speed era, that the massiveness and powering should increase 
proportionately to the capacity, or more precisely, the size of the piece 
the machine could accommodate. If there ever was any reason for this, 
there is none in the case of the new tools. Quite evidently a machine, 
say a lathe, required for working down a 4-inch bar, may be required to 
cut just as fast and to take as heavy a cut as if the bar were 12 inches or 
any other large diameter. The same gearing and powering obviously, 
then, are required for each. The exception of course is where the smaller 
machine is required for work which actually is lighter in character and 
which consumes less power. Even in such cases it is well to be on the 
safe side and to insist upon weight and power commensurate with that 
commonly found in the machine of larger capacity. The point is that 
the machine be capable of taking off and using continuously the largest 
amount of power that can be efficiently utilized by the tool. 

The Electric Drive. — While the individual motor drive has many 
manifest advantages in ordinary practice, its efficiency is not neces- 
sarily superior in all sorts of machine operation. In high-speed cutting, 
however, the largely increased power consumption and the desirability, 
in general manufacturing, of quickly stopping and starting machines 
when changing the piece under operation, strongly emphasize the dis- 
advantages of line shafting. The power lost in line transmission under 
ordinary conditions is very generally underestimated. Under the new 
conditions, wherein usually increased weight and speed is required in 
both shafting and belts, the losses are still greater and the individual 



290 HIGH-SPEED STEEL 

(or at any rate the group) machine drive comes nearer yielding a high 
efficiency, unless possibly in the case of small machines. Even in the 
latter case the group drive is preferable to line transmission of power. 
The method of applying the motor to the machine varies greatly, ranging 
from a separate motor at the ceiling, floor, or other convenient location, 
driving directly by a main belt or indirectly through a countershaft; to 
mounting it directly upon or building it around the main driving shaft 
of the machine. The latter is probably the most effective method of 
hitching, especially when the motor is of the multiple speed type; though 
the advantages of a chain drive through a variable speed countershaft 




Fig. 252. A Lodge & Shipley high-speed lathe, direct motor connected. 

or other device are to be considered where it is desirable to provide a 
great range of speed variations. The attachment of motors to machines 
through bracket extensions should be avoided. 

Use of Auxiliary Motors. — A development of the motor drive which 
is of striking advantage, especially in big machines, in that it does away 
with a number of complications arising from effecting auxiliary move- 
ments through the main drive, is the employment of subsidiary motors 
for the latter purpose. Thus we have a lathe, Fig. 238, wherein the move- 
ment of the carriage is effected by a small motor, which latter also traverses 
the movable secondary headstock. Likewise a large planer, Fig. 254, 
is provided with as many as five separate motors. The main motor 
actuates the drive, a second elevates the crosstail, a third traverses the 
head and gives vertical movement to the tool, another operates the side 
heads, and so on. The simplification thus possible, and the convenience 
of operation, are ample justification for the innovation. 

Limitations of Reciprocating Machines. — In wood working and the 
like operations, rotating tools or machines are about the only ones in 
use. There is everywhere a distinct tendency away from reciprocating 



THE NEW MACHINE REQUIREMENTS 



291 




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292 



HIGH-SPEED STEEL 



tools, with their great losses of energy through reversing, and toward 
the larger use of machine tools which rotate either the work or the tools. 
It doubtless will be a long time before the planer, the shaper and the 
slotter are entirely displaced by rotary planers and milling machines. 
The day is, however, being hastened by the apparent impossibility of 
designing or operating these types of machines to work at an effective speed 
approaching that of rotary tools. About the highest speed commercially 
practicable with a planer is about 60 feet per minute; and this is not at- 
tainable in general practice under normal conditions. If greater efficiency 
is to be attained it will doubtless be through the perfection of clutches and 
a modification of the method of changing the direction and rate of motion 
at the beginning and end of each stroke. Already progress has been 
made in this direction, and planing machines are now designed so that 
the tool starts into the work at a speed which does not damage either 
tool or machine, and is rapidly accelerated after entering the work to 
the maximum permissible in the operation of machines of this type. 

Taking Care of the Chips. — When cutting speeds and feeds are moder- 
ate, taking care of the chips presents no difficulties to speak of. When, 




Fig. 254. Chip breaker (cover removed) as used on Hartness flat turret lathe. Taken by permission 
from "Machine Building for Profit," by James Hartness. 

however, they come off so fast, as has been the case in certain instances, 
that the operator is obliged to exercise considerable agility and caution 
to avoid being entangled in and burned by the hot chips, or where it 
requires the services of two laborers to keep the machine clear enough 
of chips to permit effective operation, as was the case in a certain experi- 
ence, the problem cannot be disregarded. Unless attention is given to 
it in machine (and tool) design, steel chips are liable not only to injure 



THE NEW MACHINE REQUIREMENTS 



293 




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294 



HIGH-SPEED STEEL 



the operator, as in the extreme cases cited, but accumulate with such 
rapidity as to be otherwise troublesome. Most of the difficulty arises 
in the case of steel turning, by reason of the length of the curled chip. 
This feature is very simply cured by some device attached to the tool 
or tool post which bends the chip as it comes from the tool so it is broken 
into short lengths, say two to four inches each. An adjustable chute 
or other conveyor to carry away the short pieces is desirable. 

Summary. — The remarks here made with reference to features in 
machine tool design desirable in connection with high speed steel tools, 
are applicable (except as specifically indicated to the contrary) to practi- 
cally all types, whether used for turning, planing, milling, boring, drilling, 
or what not. The points to be emphasized may be summarized thus: 




Fig. 256. Work of the chip breaker. The six groups of short chips were produced by a chip-breaking 
turner. The fine, curling chips were not run through the breaker. Taken by permission, from 
"Machine Building for Profit," by James Hartness. 



Ample weight and distribution of material to insure the maximum 
of rigidity. 

Elimination of all joints, movements and connections not absolutely 
essential to the kind of work to be done. 

Locating tool as near the base (frame or bed) of the machine as possible. 

Strengthening of main and subsidiary drives and substitution of posi- 
tive powering for uncertain belts and step cones. 

Reduction of speed changes to the minimum required in the special 
class of work demanded. 

Direct individual motor drive wherever feasible. 

Provision for taking care of chips. . 



CHAPTER XIX. 
REMODELING AN OLD EQUIPMENT. 

To Scrap or to Remodel. — A well-established canon of industrial engi- 
neering is that if a new. machine will save its cost in five years, it should 
by all means be installed and the old scrapped. Not a few concerns 
make it a regular practice to supplant equipment, even when com- 
paratively new, with other if a saving half as great can be shown. If 
this principle were to be closely followed in all establishments, there 
would now be a great amount of second-hand machinery easily obtain- 
able. In many cases the saving to be effected by the new tools is 
insufficient to warrant scrapping existing installation. Under these 
conditions, and likewise where managerial conservatism or expediency in 
reference to capital required, make it necessary to use old machines with 
the new tools, it is important that some attention be given to the matter 
of remodeling them and bringing them into better condition to get good 
work out of the tools. Many a machine, in a general manufacturing 
shop at any rate, can by remodeling, or even by some minor changes, 
be brought into a high state of efficiency under the new conditions. 

A Case in Point. — For example, a large capacity lathe, or rather one 
of large swing, is required to take light cuts only. Its weight, strength, 
and pulling capacity ordinarily will be quite sufficient for a very con- 
siderable increase in speed, with possibly a modification of the driving 
pulley; and by similarly changing the cones of the feed drive, or better 
by substituting gears, a considerable increase in feed traverse also is 
obtainable. Such a modification practically makes a high-speed ma- 
chine of an ordinary one, adapted to the particular work mentioned, and 
is possible in a good many cases. When undertaken, however, it is 
important that the bearings be suitable to the new conditions. Other- 
wise it may be necessary to put an entire new driving head upon the 
machine. 

Simplification in Remodeling — Powering. — Such a new head, or 
possibly a modification of housings and accessory parts in the case of 
machines of other types, must be designed not only with heavier bear- 
ings, but with provisions for lubrication both ample and certain. Unless 
this is done vibration and excessive wear, with the resultant chatter- 
ing, are a natural consequence. Under the circumstances mentioned 
most machines now in use are stiff and solid enough to stand a mod- 

295 



296 



HIGH-SPEED STEEL 



erate amount of heavier duty, if the driving parts are made propor- 
tionately as effective. This is particularly true in the case of general 
manufacturing, where the work is mostly repetitive, the pieces of mod- 
erate length only, and the tools or work guided by jigs and other like 
devices. In such cases the re-designed driving parts can be very much 




Figs. 257 and 258. A drill press remodeled, to adapt it to high-speed drilling. 

Wheeler Company. 



Courtesy of Crocker- 



simplified by the elimination of all superfluous speed gears and move- 
ments intended to give facility and convenience in miscellaneous work. 
The expense of thus remodeling a machine necessarily used in general 
jobbing is not infrequently prohibitive, and about the only thing that can 
then be done is to give a little increased speed and feed, to the limit of 
the machine's capacity; and perhaps to increase the driving power some- 



REMODELLING AN OLD EQUIPMENT 



297 



what by the substitution of broader and larger driving cones. In the 
case of motor driven machines the motor should be, if it is not, capa- 
ble of carrying overload sufficient to meet the requirements of the inter- 
mittent increase in its work. 




Fig. 259. Increase in size of feed gear on an old lathe. Due to increased feed possible with, the new 
steels. One of many ways in which old machines may be rebuilt to meet the new conditions. 




Fig 260 Effect of increasing materially the pull upon a planer not designed for high-speed service, 
and a method of prevention. Steel gears are preferred, but in this case a steel nm was shrunk upon 
an iron hub as an emergency measure, and worked all right. Courtesy of Mr. tt. W. Jacobs. 

Special Attention to Gears.— In overhauling a machine with a view to 
use with high-speed tools it is essential that all gears should be replaced 
which are much worn or which are not both truly made and strong 
enough for the new service. In many cases it may be necessary to 
replace cast-iron gears with bronze or steel ones, or where they are large 



298 HIGH-SPEED STEEL 

enough to warrant, with steel rimmed (and preferably also steel or 
bronze bushed) wheels. Especially in reciprocating machines like 
planers, any large augmentation of the work done is likely to be accom- 
panied by a stripping of gear teeth during the reverse and the starting 
of the tool into a fresh, cut. The stopping and the sudden starting 
absorbs an amount of power frequently not suspected; and the momen- 
tum is greatly increased by the additional speed — where the design of 
the machine will permit such increase. To provide against stripping 
under these circumstances the gears must be strengthened as already 
indicated. 

Modification of Reciprocating Machines. — Sometimes a machine of 
this reciprocating type, not otherwise capable of increased speed but 
strong enough to stand it, can be better adapted to the new tools by a 
re-designing of the driving apparatus and the use of clutches or the 
modification of those already in use. At the least it is usually possible 
to increase cuts, even if not speeds, through such modifications. 

As to Worn Machines. — Concerning the many machines likely to be 
found in a shop devoted to general manufacturing, machines likely to 
have been in service for some time and therefore more or less worn, not 
much can be said without an understanding of the particular conditions. 
Often nothing is possible except to take advantage of the longer wear 
of a tool, that is, the less frequent need for grinding, while running at 
the usual speeds, though possibly with some increase in feed. In other 
cases it is possible, and therefore expedient, to run at the highest speeds 
possible without remodeling the machine, getting all possible out of it 
within the shortest time, then scrapping it when too much worn to 
work with sufficient precision and freedom from vibration. 

Spring in Frames. — In machines like drills, and even planers, espe- 
cially when the housings are considerably separated to allow large pieces 
to be worked, there is likely to be more or less spring in the rail or in 
the parts bringing the tool and the work together. This is bad enough 
when ordinary tools are used, and is the frequent cause of tool breakage, 
especially of drills; but if advantage is to be taken of the higher speeds 
and feejis often possible, attention must be given to so strengthening 
these parts or so supporting them that there shall be no spring. If the 
frame of such a drilling (or other) machine is weak, little, if anything, 
can be done. If the trouble lies in worn bearings for the brackets 
supporting the table, or to spring in them, they can usually be solidly 
blocked against the base and the proper degree of rigidity secured. 

Spindles and Tool Position. — It should go without saying that worn 
spindles are not permissible in high-speed work; and if there is no pro- 
vision for taking up the wear, they would better be replaced. The same 
thing is true of all studs and other bearings, and applies as well to all 
slides and adjustments. In many cases these need strengthening as 



REMODELING AN OLD EQUIPMENT 299 

well as refitting, and usually also may be modified so as to bring the 
tool position nearer the supporting frame or bed and thus decrease the 
liability to chatter. All slides and adjustments not absolutely neces- 
sary should be eliminated and the tool holding and adjusting parts made 
as rigid as possible. 



CHAPTER XX. 

STATEMENT OF THE PROBLEM. 

Position of High-Speed Tools. — Revolutions do not usually happen 
in a moment, in the industrial world. Perhaps it were better to say, 
they do not happen at all; for industrial progress is evolutionary rather 
than revolutionary. A new invention does not immediately upset 
prevailing conditions, but gradually takes its proper place as an economic 
factor while it is being developed and adapted to existing conditions — 
or as not infrequently happens, while conditions are changed to meet 
the new order made possible. So it has been in the case of high-speed 
steels. Their capabilities and limitations are by no means definitely 
fixed even yet, though they have already taken a place in production 
engineering important to a degree scarcely equalled by any other discov- 
ery in recent years. Along with improved methods of rapid transport 
and handling of materials, and of rational organization and administra- 
tion, the new tools are surely, if not precipitately, bringing about a new 
order of things in the metal industries, and to a considerable extent also, 
indirectly, in other industries apparently not closely related. 

Cost Reduction as High as One-Third. — A manufacturer of large 
interests is quoted as saying that in his plant the cost of producing 
machines has been reduced a fourth to a third, directly through the 
economies permitted by the use of high-speed steel tools and the indirect 
economies necessitated by the reorganization of the shop methods and 
shop administration. This may be an unusual case; perhaps it could 
not be duplicated in a manufacturing plant producing a greater variety 
of output. Perhaps also it is not possible in many cases (though parallel 
instances could be mentioned) to find, as in this one, that the labor-time 
on a single piece could be reduced as much as 95 per cent, the product 
being at the same time better than before. 

The Case of Tire Turning. — The turning of locomotive drive wheel 
tires, to mention a case under different conditions, likewise is indicative 
of the wonderful development in metal cutting possibilities. Not so 
long ago one and a half to two days was the time commonly consumed 
in turning up a pair of drivers; and very recently indeed, the perform- 
ance of the job in half a day, or a little less, was looked upon as a feat 
worthy of attention. Now, however, it is not only possible, but it is a 
regular commercial performance, to turn up badly worn tires as large 

300 



STATEMENT OF THE PROBLEM 



301 



as five feet in diameter, at the rate of a dozen or so in a day of ten 
hours — the time required for placing and removing the wheels included. 




Fig. 261. Turning locomotive drivers at the rate of a dozen or more pairs a day necessitates facilities for 

rapid handling, as here shown. 



Astounding Economies not to be Expected. — The publicity matter of 
high-speed steel makers and sellers sets forth in glowing terms examples 
of wonderful performances and astonishing savings effected. There is 
no need to question the accuracy of the instances cited. Doubtless 
even the most extravagant is capable of verification; and certainly 
none is likely to be more wonderful than those mentioned above, or than 
such as might be found in almost any average shop. Manifestly, how- 
ever, such remarkable savings are not possible in all cases, nor perhaps 
even in many, considering the great diversity of conditions affecting 



302 HIGH-SPEED STEEL 

the different kinds of jobs in general manufacturing, and the differences 
in efficiences everywhere existing. Indeed, the authority just quoted 
particularly mentions that in his own business of machine building, 
roughing work, in which he makes the greatest showings, does not exceed 
one-third of the work required, and that consequently a very large part 
of the saving is on this third part. It is not at all necessary that such 
showings should be common. The ordinary performances of the new 
tools, even under conditions allowing only moderate efficiency, are 
marvelous enough. 

A Modern Miracle. — The possibility of cutting refractory metals almost 
as if they were cheese is another of the modern miracles — a miracle 
already become commonplace. Only recently cutting at something like 
20 feet a minute was considered reasonably satisfactory; and this rate 
was probably above the> average in most shops, though indeed speeds 
as high as 60 feet per minute were not unheard of, and some considerably 
higher than that are recorded as having been attained. So far as can 
be learned the maximum speed attained with carbon steel tools was 
about 100 feet per minute; and this was under the most favorable con- 
ditions of cooling and chip removal, conditions involving a complicated 
system of appliances and devices scarcely applicable to ordinary com- 
mercial work. Half as great a speed may well be considered to have 
been the commercial limit, under the old conditions — a limit not 
attained in practice to any considerable extent. 

The Passing of Traditional Conditions. — Such speeds, or rather such 
extreme lack of speed, was in a sense distressing in an age where rapidity, 
time-saving, nerve-racking haste has come to be characteristic — where 
seconds count as hours did not in times within the memory of most of 
us. The days are past, or at any rate are swiftly passing, when it is the 
regular thing to see a piece of metal lazily creeping round and round, 
the tool paring it down at a snail's pace; the operator the while listlessly 
lounging near, merely keeping an eye upon the machine to see that all 
is going properly. And it is well that it should be so. Efficiency is 
come to be the watchword of modern civilization, and of industry the 
slogan. Hence the new tools, or possibly newer ones of still higher 
possibilities, must eventually crowd out the less efficient wherever 
efficiency counts, and must at the same time bring about very great 
concomitant changes in all the conditions touching or involved in the 
metal working arts. 

But these changes are not yet accomplished, taking productive in- 
dustry as a whole. They are only in process, and completed, relatively 
speaking, only in isolated industrial units. Hence it is worth while to 
inquire into the situation, not so much perhaps to discover why high 
speed steel tools are as yet used so little, comparatively, as to determine 
if possible what problems are to be solved, and how, in order to take the 



STATEMENT OF THE PROBLEM 303 

fullest advantage of the new steels consistent with expediency. So 
much, at least, should be done in all cases. Only that ultra conservatism 
which spells bad management would permit less. 

Non-Uniformity of Material. — A serious difficulty in not a few shops 
is that connected with the lack of uniformity in the hardness of the 
material to be machined — a difficulty which sooner or later is en- 
countered in every shop. Castings every once in a while, for some 
unaccountable reason possibly, come so hard as to play havoc with 
ordinary tools. Occasionally the same thing happens with steel stock. 
Only a few pieces at most can be finished until the tool requires re- 
grinding. Possibly, in extreme cases, several grindings are necessary in 
order to finish a single piece. Or it may be the stock specified and 
required in a given part, is uniformly so hard as to be practically beyond 
ordinary tools — even mushet steel being able to make but a sorry show- 
ing. Instances of this sort are by no means infrequent; and there can be 
no question as to the expediency of using high-speed tools, even though 
there be no gain in speed or cut — as most often there may be, never- 
theless. The gain here will certainly be great if only the loss of time 
in grinding and setting tools be taken into account; and it is likely to 
be considerably augmented by the saving which arises from the elimi- 
nation of the need for scrapping many parts because of inaccuracy such 
as necessarily accompanies those conditions, when only carbon steel 
tools are available. 

Especial Field for High-Speed Tools. — The especial field for high- 
speed steels, or rather the kind of work in which it shows up most favor- 
ably, is that involving the removal of large quantities of metal, as has 
been pointed out elsewhere. Here the Taylor doctrine of running tools 
(these having been suitably designed, standardized, and treated,) at 
speeds high enough and feeds and cuts heavy enough to necessitate 
re-grinding at intervals of about one and a half hours, can be practiced 
to the best advantage; and here it is that there is most reason for his 
dictum that the one who does not do so, does not know how to cut 
metals most efficiently. 

Scrapping not Generally Warranted. — Saying nothing of the great 
variety of work where heavy cuts are not only unnecessary, but undesir- 
able, and where the highest speeds are impracticable, it is to be observed 
that the conditions of maximum effect are dependent not alone upon 
the tools, but upon a considerable number of concomitants, the most 
important of which perhaps is the machine equipment. Obviously it 
is desirable that this latter should comport, in possibilities, with the 
tools as applied to the particular jobs. But average machines as hereto- 
fore used, and still in use for the most part, by no means measure up 
to this standard. In a few instances concerns have adopted the radical 
policy of replacing entirely all equipment not capable of using the new 



304 HIGH-SPEED STEEL 

tools to their maximum capacity, with other that is so capable. Clearly 
such a policy is in line with " good business " when the economies to 
be effected are great enough to warrant the expenditures. But in 
miscellaneous manufacturing it seems quite certain that they are not 
always so. Take for example that very large class of operations upon 
small pieces reduplicated in large numbers and generally requiring but 
little machining: The limit of the operator's endurance, and therefore 
the limit of output (except possibly through the adoption of an auto- 
matic machine — which is as yet impracticable in the vast majority of 
cases), has under these circumstances usually been reached. 

Place of the Automatic Machine. — Of course if an automatic machine, 
or even a semi-automatic requiring a minimum of attention and skill 
from the operator or attendant, is feasible — which is to say, if such a 
machine can be built without being very complicated and expensive 
to maintain — the problem changes again, and it would be desirable 
to build the machine. But whether this be feasible or not in particular 
cases, there is a side to the high-speed problem often overlooked, in this 
very matter of the endurance limit of the operator and the related 
psychological and sociological effect of the deadening monotony involved 
in feeding stock into, and practically becoming an attachment of a 
machine. This is not deemed the place for a discussion of this aspect 
of the new-tool problem; but it is an aspect which will year by year 
become more insistent for solution and which must sooner or later be 
squarely faced. And when that situation arises, the indications now 
are that the increased development and use of the automatic machine, 
with its large possibilities in the way of high-speed tools, will be an 
important factor in the ultimate solution. 

Limitations Imposed. — Not only is equipment wanting, in the great 
majority of cases, but expediency prevents the scrapping of machinery 
still in good, or even in moderately good condition, and the consequent 
large expenditures for new. On the other hand also there are a good 
many jobs where the inherent conditions are such that the machines in 
use are quite competent to do all, or nearly all, that would be possible 
in any machine — where the efficiency of a cutting tool is to a consider- 
able extent limited by the nature of the job itself. Take, for example, 
the machining of a heavy casting, where the machining itself amounts 
to little and occupies but a small fraction of the total time necessary 
for the complete operation. Increased cutting speed manifestly would 
be of no considerable advantage; and neither would heavier feed; like- 
wise there could be nothing gained by deeper cats, except in special 
cases, for these would merely involve molding the casting larger than 
necessary, for the mere sake of removing it again. The special cases 
would be typified by that wherein it is required to mold the casting 
considerably heavier than the finished size in order to minimize distor- 



STATEMENT OF THE PROBLEM 



305 




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306 HIGH-SPEED STEEL 

tion or possible breakage during a series of operations, or where the 
nature of the casting partly chills the surface to be machined or leaves 
it with a skin naturally hard on a cutting tool. Here a deeper cut would 
be desirable; but the machines already installed generally would be 
quite able to take care of the increase required. 

Two Extreme Classes of Jobs. — From jobs of these sorts it is a far 
cry to those at the other extreme where long and heavy cuts and high 
speeds are obviously the thing; and between these extremes lie jobs 
of all gradations as to cutting possibilities. Lying in the lower ranges 
would be those where the only economy in high-speed tools would be 
the lowered cost of tool and tool maintenance, and those where under 
prevailing or former conditions many pieces were necessarily scrapped 
because of breakage or imperfect workmanship. The apparent paradox 
of cheaper tools is touched on elsewhere, but may be said here to refer 
to the relatively long life of such tools, the more particularly of com- 
posite tools, and the consequent distribution of tool cost over a very 
greatly increased product. The scrapping of many pieces which has 
seemed necessary to and inherent in tools and methods heretofore in 
use, can be eliminated to a material extent through the use of high- 
speed tools, in most instances without any change in machines. Such 
a saving may easily be considerable while still not appearing in a 
changed labor rate. 

Operations with Short Cutting Times. — Referring again to jobs such 
as have just been mentioned, where the cutting time is relatively small: 
there may be many such where it is quite possible to use higher speeds 
or heavier feeds to such an extent that the cutting time becomes negli- 
gible, or nearly so ; and thus the second or third machine which is under 
present, or was in recent practice necessary to keep the operator busy, 
can be dispensed with and capital (and consequently depreciation, repairs, 
etc.) thereby reduced while at the same time available floor space is 
increased. Here also there would be a saving quite appreciable, which 
nevertheless would, under usual methods of cost accounting, not appear 
in labor cost — a saving which might, or might not, necessitate the 
installation of a heavier machine, according to the conditions in par- 
ticular cases. 

Immediate and Ultimate Considerations. — Evidently the problem is by 
no means, or at any rate not at all necessarily, one of disposing of old 
and installing new equipment throughout an average plant. Unquestion- 
ably high-speed steels, if the standing offer of certain makers to replace 
with positive economy any ordinary tool with one of their own make 
can be backed up, are bound ultimately to displace almost, if not quite 
entirely, the less efficient kinds. Even now it is not so often a question 
as to whether or not a high-speed tool shall be used, but rather as to 
expediency in reference to the equipment in which the tools must be 



STATEMENT OF THE PROBLEM 307 

operated. Ultimately of course the question of profitableness will 
determine, as it does practically all questions in industrial engineering; 
and if, when all is said and done, a new tool or a new machine, or both 
in conjunction, will yield a product cheaper and better than before, then 
the old must inevitably give way to the new sooner or later — and 
usually sooner than later. For the present, however, the problem, 
in so far as it concerns the shop or factory in general rather than those 
special cases already indicated, seems to be less a general than a specific 
one. In an offhand way it may be said with assurance, almost as a 
matter of course, that high-speed tools should be used to the largest 
possible extent in all metal-cutting shops. But the real question is, 
just what shall be done in this or that specific, particular instance? 

How the Problem Works Out. — Here is a job, let us say, to be performed 
under definite conditions; and such and such machines are available for, 
■ or possibly are actually performing, the operations. Is it possible to 
reduce the cost of these operations, or specifically this one operation, by 
the use of a high-speed tool and heavier or faster cutting? If so, to 
what extent are the available machines capable of realizing the ideal 
conditions, if utilized without modification? If this performance falls 
short of the attainable maximum, can the machine be altered or rebuilt, 
without prohibitive cost, so as to yield this maximum while still not 
working disaster upon the machine and wiping out the gain through 
heavily increased maintenance cost? This latter point is one seriously 
to be considered, in connection with the subject of equipment in gen- 
eral, as well as in connection with specific cases. It is found possible 
to speed up a machine still quite serviceable under ordinary conditions, 
so as to yield a considerably larger output; but directly it may be found 
also that gears break frequently, and belting gives out rapidly, and the 
expense of repairs in general is possibly as much as doubled. This of 
course does not always take place; but it may do so, and is frequently 
to be expected. The limit of the machine's endurance, that is, the 
point beyond which maintenance cost becomes excessive and expensive 
delays through breakdowns are invited, is carefully to be considered; 
and along with it the rapid wear under the severe conditions for the 
meeting of which it was not designed. 

The Power Problem to Receive Attention. — Furthermore, the matter 
of power consumption needs attention. Not that the increased amount 
of energy required for taking care of the greater amount of work done 
need occasion serious concern. Under proper conditions the total 
power required for doing a given amount of metal working will actually 
be less than under old conditions, though indeed it becomes necessary 
to concentrate or localize it largely, so to speak. In attempting to 
speed up old machines designed only for moderate speeds, the amount 
of power absorbed by the machine itself, not considering at all that 



808 HIGH-SPEED STEEL 

entering into the cutting, may easily become surprising. It is not so 
unusual as might be supposed in the absence of actual measurements, 
for a half of the total power delivered to a machine to be thus absorbed 
in overcoming friction. Under such circumstances the speeding up of a 
whole plant would evidently necessitate a very large augmentation of 
power plant capacity. 

When a Machine is to be Superseded. — When it is evident that a 
machine already installed cannot economically or effectively meet the 
desired requirements, the question arises as to the displacement of the 
machine with one capable of yielding the maximum output with min- 
imum maintenance and operating cost. Questions of temporary expedi- 
ency aside, there are pretty definite conditions, though varied according 
to the nature of the individual cases, under which a new machine should 
replace an old. Quite plainly if the required output involving a par- 
ticular job or a closely related class of jobs is sufficient to keep the 
machine busy practically all the time, and the required increase in out- 
put must be met by additional equipment anyway, it is then not only 
desirable to install an up-to-date machine, which by its increased effi- 
ciency will be able to take care of the required increment, and probably 
more; but it is folly not to do so. Even though the machine be idle 
a considerable portion of the time under the new conditions, the econ- 
omy is like to be more than great enough to warrant the change; and the 
same often will be found true when even the old machine is not used 
nearly to its capacity. The common rule that a machine is to be replaced 
whenever a yearly saving or ten to twenty per cent of its cost can be 
shown, has been referred to already. In the consideration of such 
changes it is to be remembered that a machine not sufficiently produc- 
tive or powerful to allow efficient use upon one job or class of jobs, may 
still be suited to economical work upon another whose requirements are 
less rigid; so that the displacement of a machine is not necessarily the 
same as scrapping it. 

Re-design of Jigs, etc. — Not only must the machine be capable of, and 
adapted, so far as may be, to heavier duty, generally speaking, but 
especially in reduplicative work jigs and other holding or guiding devices 
will need re-designing or remodeling. Magnetic or air chucks and jigs 
will largely displace the cumbersome lug or screw fastened holders still 
generally used, so that a piece of work, or a number of pieces simulta- 
neously, can be instantly fastened securely and held firmly during the 
operation, and as quickly released when the job is completed. Like- 
wise it will be necessary to devise something more substantial for hold- 
ing work turning on centers than the bent tail dog, whose wagging is 
not tolerable under the new conditions. 

Manufacture or Purchase of Tools. — Intelligent production and han- 
dling of the tools is a factor in high-speed production second in importance 



STATEMENT OF THE PROBLEM 



309 



to none other. The actual making of tools is best not undertaken at 
first, except perhaps in large plants. They can be readily purchased 
made up to specifications fitting them- for the particular work required. 




Fig. 263. End milling. 



Use of magnetic chuck for quickly clamping and securely holding work. 
Courtesy Cincinnati Milling Machine Company. 



The purchase of all standard tools will be most economical, in general, 
for all shops except possibly those especially equipped for their manu- 
facture, though it may well be that such simpler forms as lathe tools 
and the like can be produced within the plant itself. Even this is not 
advisable unless there be suitable facilities and tool-makers expert 
enough to make tools of uniform and high standard quality. Experi- 
ences with tools manufactured under uncertain conditions and by inex- 
perienced hands, and therefore of uncertain quality and uniformity, are 
likely to prove unsatisfactory and disappointing. In the beginning, at 
least, it is safest to buy all tools ready made, gradually training tool- 
makers to the proper handling of the new steels and substituting for 
those made outside only as experience shows the possibility of producing 
within the shop others equally certain in quality. An alternative of 
course is the employment of one or more experts to undertake the tool- 
making problem, and in large shops to train the rest of the tool makers 
to the new tricks of the new trade, so to speak. Unquestionably this is 



310 HIGH-SPEED STEEL 

an excellent thing to do anyway, in places where many tools are manu- 
factured; and even then it will be no day's task to educate men brought 
up under the old conditions to the new requirements in tool making. 

Expert Direction. — Such an expert might have charge also of the 
development of the high speed steel problem throughout the plant, with 
a large responsibility in the matter of educating the machine operatives 
also, to the new situation. The old proverb holds good in industry as 
elsewhere — it is hard to teach an old dog new tricks; and it takes time 
and not a little persistence to educate a man out of the 25 foot speed 
and sV inch feed rut and induce him to take advantage habitually of 
cutting rates three and more times those to which he has been accustomed, 
even if he be willing to learn. The new tools can do much; but they 
cannot make an industrious workman of a lazy one — any more than 
they can increase the physical endurance of one already pushed to the 
limit under the old conditions. Where this limit is reached, as shown 
before, an entire change in the method of doing the work — perhaps 
by the substitution of automatic machinery — is the obvious thing to 
do. If not, it is desirable that the hearty co-operation of the workmen 
be secured. 

Attitude of Operatives. — Not that operatives in general do not take 
kindly to the new tools. On the other hand they all but invariably 
welcome and eagerly desire to be permitted to use them. But it not 
only requires an expert knowledge of conditions and of the possibilities 
of the individual cases so to set the pace or change conditions that the 
highest attainable efficiency shall be insured; but also it is essential that 
there be held out, through a rational and just wage system, like the 
premium plan, say, such incentive as will stimulate ambitious workmen 
to raise their own efficiency; and that at the same time there be super- 
vision so skilled and so organized that guesswork in machine operation 
is minimized or entirely eliminated, and conditions hindering maximum 
efficiency changed so as not only to permit but to compel it. 

Maximum Production — Auxiliary Conditions. — Precisely here it is 
that a great mistake is often made in high speed tool practice. The 
subject has scarcely yet been approached, much less reduced to definite 
standards fitting all cases. It is true that Mr. Taylor and his associates 
have succeeded in reducing practice in certain works to a very definite 
basis; and they have obtained results nothing short of phenomenal. 
Equipment, tools, auxiliary methods, and even administration, have 
been revolutionized to create conditions making for greatest efficiency; 
and everything (or almost everything, it would seem) is definitely and 
specifically worked out by the slide rule, and by effective supervision 
the standards thus set are actually attained and maintained. All this 
goes to show, as do similar experiences elsewhere (possibly carried out 
less consistently), that the problem of high-speed tools involves not only 



STATEMENT OF THE PROBLEM 



311 




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312 



HIGH-SPEED STEEL 



the matter of tools and machines, but is vitally concerned with the sub- 
ject of shop organization and necessitates methods of supervision and 
co-ordination very much in advance of those customarily in vogue. 
It is important, that is, not only to determine beforehand with practical 
accuracy the machine to be used for a particular job, and the most 
efficient speed, feed and cut, and the precise manner and order of doing 
the work; but for profiting to the largest extent by this possible acceler- 
ation, the movements of material, the facilities for storage, the supply 
of sharp tools and the method of distributing them — all these and 




Fig. 265. Auxiliary storage for materials in process requires much space around the machine or in- 
volves the large use of conveying or transportation units, as in the case of this overhead trolley system. 
From the main trolley track switches run to every erecting jack in the room. The assembled machine is 
tipped from the jack onto the hooks of the trolley, shunted out upon the main track, and propelled to the 
paint shop by a motor-actuated endless chain provided with suitable fingers. 

other ancillary activities, systems, and methods concerned in the con- 
version of material into product, may need, and probably will require, 
entire reorganization. Thus, concretely, it boots little that an indus- 
trious and ambitious workman be provided with the most approved 
superior rapid-cutting tools operated in the most up-to-date machine, 
the most efficient rates of cutting carefully prescribed, and working 
under a rational premium or other wage system urging him on to the 
exertion of his maximum efficiency, if at the same time, he is obliged at 
intervals to loaf or dawdle along while, waiting for material, because of 
inadequate means of transporting and handling the same to and from 



STATEMENT OF THE PROBLEM 



313 



his place of work, insufficiency of stock or of storage facilities for material, 
or a stinted supply of sharp tools. 

Material Handling — Change in Methods. — More than likely acceler- 
ated production under the new conditions will mean, in most factories, 
a complete change in the methods and facilities for stock storage, the 
providing of more room and better access so as to permit handling to 
and from storage with the greatest convenience and ease. Heavy 
parts, as well as light, will need to be so stored, and means for mechan- 
ical handling so provided, wherever necessary, that the movement and 




Fig. 266. After passing the dipping tank the trolley and its load are switched from the trunk track to 

storage tracks for drying. 



handling shall involve a minimum of effort, of time-labor. The subject of 
auxiliary storage, storage for material in process of manufacture while 
passing from one operation to another, becomes highly important. 
More room will be required around a rapid production machine than 
ever before; but not necessarily for storage bins. These may well be 
required; but if so, ought to be of such type that they can be emptied 
into transports of appropriate sort with practically no handling, or to 
be so placed as to permit their being reached without any transport, 
by the operator to whom the parts next pass. 

Auxiliary Storage and Transportation. — The auxiliary storage will 
most likely need to consist mainly in a very materially increased number 



314 



HIGH-SPEED STEEL 



of transport units — cars, trucks, trolleys, or whatever such units may- 
most conveniently consist of, to meet the requirements of the particular 
kinds of parts to be transported. Hand trucks, of approved types only, 
may perhaps still be used, in larger numbers than ever before; but the 
relative inefficiency of man power, as compared with mechanical, indi- 




Fig. 267. 



Auxiliary storage by hand trucks. Very well if trucks are designed to fit the conditions and 
do not occupy an amount of space not permissible. 



cates the need for displacing hand trucks to the largest possible extent 
by conveying units capable of being mechanically moved. The trans- 
portation system therefore will need overhauling and remodeling, with 
a probable large increase in capacity and a close interrelation of the 
various constitutents. The standard gage and industrial railway, the 
crane service, the overhead trolleys, belt and other mechanical conveyors, 
and also hand trucks where these are retained, must be so interrelated 
and efficiently operated that material will move rapidly, without unneces- 
sary interruption, and in sufficient quantity always to insure a minimum 



STATEMENT OF THE PROBLEM 315 

of lost time at the machines as well as while in actual transport. The 
desideratum will be rapidity of movement as well as ample sufficiency 
of portable storage capacity (the elimination so far as practicable of 
man-power trucks being taken for granted), so the material can pass 
along through the several processes of manufacture with least loss of 
time and the fewest number of handlings. 

Problem of the Tool Room. — The tool-room problem likewise assumes 
a place more important than before. It is necessary that the supply of 
tools be ample, which is to say, much larger than under old conditions; but 
the system of stocking and distributing must be greatly improved. Red 
tape will be eliminated so far as possible, and provision made whereby 
the workman can quickly communicate his tool needs and have them 
quickly supplied. This may mean electrical communication in connec- 
tion with mechanical or pneumatic carriers, or perhaps the latter alone. 
In plants where the highest organization is for any reason impossible, 
it may mean electrical communication of some simple sort, in connection 
with boy-transportation of tools. But at any rate it means a change 
from present methods, as usually found, to others more in harmony with 
the spirit of accelerated production. 

Tool Supply and Maintenance. — This phase of the problem (the tool 
supply) is concerned also with questions affecting the length of time it 
is expedient to run tools in particular cases before re-grinding, which in 
turn is related to that of standard speeds and feeds; and may mean the 
revolutionizing of the system and methods of sharpening tools. This 
latter evidently will need to be done by inexpensive labor, in grinders 
designed to operate with precision to give standard shape to cutting 
edges with minimum skill, and involves the adoption of a complete 
system of standards and specifications with respect to tool shapes. 
It likewise involves such storage facilities for tools that they will be 
least likely to sustain damage (nicked cutting edges, and the like) in 
the storeroom, and can be dispatched and delivered with promptness. 
There come in also such matters as more complete standardization and 
interchangeability of the parts manufactured, where this is not already 
carried as far as possible; and the maximum use of gages requiring a 
minimum of time and skill to use, even where jigs can be used most largely. 

The Array of Problems.— Such an array of intimately related problems, 
all affecting the most efficient use of the new tools, may well lead to hesi- 
tation in the adoption of high-speed steel as the standard tool material. 
It may seem in some cases to involve an entire reorganization and more 
or less re-equipment of the whole factory, and at the least a wide depar- 
ture from existing conditions. As long as it will pay increased returns to 
both factory owner and worker, clearly the new should displace the old. 
Gradually, of course; for revolutions such as these, as pointed out in the 
beginning, must take place naturally, else the whole business is like to 



316 



HIGH-SPEED STEEL 




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9^ 



as 



STATEMENT OF THE PROBLEM 317 

be put out of joint. And ultimately the change must come, willy- 
nilly, even to the most conservatively managed shop. So long as com- 
petition shall be the basis of business, ever growing keener as it must, 
the law of survival of the fittest will eliminate from that competition 
any business which neglects to take advantage of every opportunity for 
increased and more economical production, such as is offered in the 
metal industries by the extensive use of high-speed steel. 

Expert Assistance Desirable. — And who is sufficient for all these 
things? The factory manager as he is, and his force of lieutenants, 
possibly may not feel equal to such a reorganization, and probably also 
are in no position to give attention to the working out of all the details. 
The employment of an expert to take charge of this part of the situa- 
tion has been already suggested. Experienced engineers stand ready to 
undertake just such commissions; and it is merely a matter of time and 
capital to bring any plant to the highest possible state of efficiency. 
The lack of the latter item, sufficiency of capital, will of course delay 
the complete carrying out of plans for maximum productive capacity 
at minimum cost in a good many instances, but should by no means delay 
the undertaking and its accomplishment as rapidly as circumstances will 
permit. 

The Situation Summed Up. — Summing up the situation as it confronts 
the factory manager, it seems to be about like this: 

Old tools are to be displaced wherever it can be shown that the time 
saved in grinding and the tool cost per piece finished, even if there be no 
gain in rapidity of operation, shows a substantial saving. The new 
processes of manufacturing composite or compound tools reduce the 
cost to such an extent that the difference between their first cost even, 
and that of the old kinds, is not great enough to be seriously considered; 
and not infrequently actually allow tools to be made cheaper than before. 

Old machines can be utilized in many cases almost or quite as effi- 
ciently as new ones, in the general run of manufacturing; and when not, 
can often be remodeled to a greater or less extent, as the conditions in 
the case warrant, so as to be moderately well suited to the new require- 
ments. In many cases the old machines will be unsuited to the heavier 
duty necessary, and will need to be displaced by new, of types designed 
with the special conditions in view. Such new machines, in general 
manufacturing involving the reduplication of parts, will be as simple 
as possible in construction, with all unnecessary movements and adjust- 
ments eliminated. For shops producing mainly such things as require 
or permit the removal of large "weights of metal, machines of extraor- 
dinary strength and power will be required. 

The workman himself is an important factor in securing the largest 
returns from the new tools, and his co-operation is to be secured through 
a liberal wage system whereby he, as well as his employer, profits; and 



318 HIGH-SPEED STEEL 

his work is to be so adjusted that when working at maximum efficiency 
his physical strength and endurance are not overtaxed. 

The tool department will need to be carefully adjusted to the new 
conditions, the tools themselves being made within the shop or pur- 
chased outside, as may be most expedient. In the former case it is 
absolutely essential that there be expert toolmakers who shall be able 
to turn out tools of the very best quality, and in the latter case it is 
important that the tools be bought according to specifications fitting 
them to the special work required of them. The distribution of tools, 
and their grinding and keeping in condition, will be so organized that the 
workman himself is relieved of the need for attending to the matter, 
while promptly supplied as his needs may require. 

Transportation and storage facilities, especially auxiliary storage for 
materials in process, must be adapted to the accelerated production, and 
so co-ordinated as to eliminate all unnecessary handling and all delays 
occasioning idle machines and workmen. The transportation system 
will have its units so adapted and of such number that they will in large 
part serve for the auxiliary storage. Stationary storage, whether for 
stock or material in process, is to be in such form as to eliminate handling 
as far as may be, and to facilitate handling where this is necessary. 

And finally, supervision of the highest order of intelligence, as applied 
to the special problems involved in the use of the new tools, is indispen- 
sable. It is necessary to determine beforehand what shall be the time 
and method of doing given jobs, fixing these elements and the labor cost 
at the same time, on a rational basis instead of by guess; and likewise 
to see to it that the conditions laid down are faithfully carried out. 
Such special supervision may be trained up within the plant itself; but 
in general it will save time and insure greater efficiency if the reorgani- 
zation be done through some outside agency, say through industrial 
engineers thoroughly familiar with the new conditions. 



CHAPTER XXI. 

MAKING A BEGINNING. 

About Tests. — About the first thing considered ordinarily, after it has 
been decided to use high-speed tools, is the making of tests to determine 
the best steel for the purpose. Much good money is wasted in this way, 
and not. a few disappointments grow out of such misdirected zeal. Not 
that all such tests are useless. They have their place — which, however, 
is not at the beginning of one's high speed tool experience. There are on 
the market a great number of the new steels, possibly more than a hundred 
by this time; and while they vary more or less among themselves as to 
composition, and therefore as to special adaptation and universality of 
use, almost any one of them put forth by a manufacturer of repute will 
do as well as another while a beginning is being made and the local 
problems investigated. In the meantime the simpler, as well as the 
better way, is to select some one standard make of steel, and use it 
exclusively until there shall have been sufficient experience in the making 
and use of the new tools to permit intelligent experimentation and 
rational conclusions. Besides the small value to be placed on tests 
conducted by neophytes, or even by experts, for that matter, under 
conditions not thoroughly understood, there are several manifest dis- 
advantages in keeping on hand a supply of each of several kinds of steel, 
and making or using several kinds of tools for the same work. All these 
difficulties and disadvantages are avoided if, as suggested, but one make 
of steel is selected. Obviously the selection must be made with some 
care, so as to make it reasonably certain that the steel adopted for the 
time being shall be well adapted to the general run of work done in the 
shop. It may be mentioned in passing that cheap high-speed steels are to 
be looked upon with suspicion — at this early stage of experience at any 
rate. 

Scope of Profitable Experimentation. — Neither is it worth while to under- 
take expensive and long drawn out experiments (others would be of small 
value) to determine cutting angles, tool shapes, standard speeds, and 
the like data of a general nature, as a basis for the introduction of high- 
speed tools. It may be possible to improve upon the determinations 
already made by others, or possibly to modify now accepted conclusions; 
but experiments looking toward this end may well be left until later in 
one's experience, and the laws and facts already established and avail- 

319 



320 HIGH-SPEED STEEL 

able for reference adopted, for use until mayhap better can be found in 
the natural course of events. 

It may be said in passing that to carry on a series of experiments 
such as these, so the results will have positive value, requires much 
experience and clear thinking, and involves a preliminary arrangement 
of conditions not always easy to secure. Thus, to mention a single 
point, in testing one steel against another, the results will be of little 
value unless the tests be made at the same time, on the same piece of 
work or on pieces ascertained beyond doubt to be of exactly the same 
characteristics as to hardness, etc., with the same feed, speed, and cut, 
on the same diameter, with tools of precisely the same form and treated 
so as to develop the maximum possibilities of each — which treatment 
may perhaps not be exactly the same for both tools. If allowance has 
to be made for variation in any one of these conditions, the comparative 
values cannot be established with certainty. The introduction once 
made and the new methods once fairly established, the workmen edu- 
cated to the proper management and use of the new tools, there will be 
time enough to carry out any such comparative tests as may be found 
desirable. Especially if it is attempted to manufacture all, or perhaps 
but a few, of the tools, even under the direction of experts familiar with 
the new steels, there undoubtedly will be enough troubles and problems 
without the additional distractions incident to such tests. 

Each Plant a Problem in Itself. — In making a beginning, sweeping 
changes will be avoided, the development of the problem taking a natural 
course which will merely modify conditions as fast as expedient, until 
the whole situation shall have been harmonized with established best 
practice. Any business organization, particularly that of a big factory, 
is a delicately balanced mechanism which cannot well be rudely dis- 
turbed without unlooked-for consequences. In the preceding chapter 
the sweeping nature of the changes generally requisite for high efficiency 
have been indicated. However, it is not only inexpedient to make such 
a change suddenly, but practically impossible. The study of the local 
problem in any particular plant, the determination of what is best in the 
case of each of the possibly several thousand operations there performed, 
will require a long time and much patient study. The obvious thing 
is to place the undertaking, as already recommended, in charge of a 
competent man or a group of men selected primarily because of their 
experience with the new tools and their open-mindedness toward new 
ideas. The fixing of responsibility in one or more persons is very im- 
portant. If the matter be left to the several foremen, the work will of 
necessity be more or less haphazard, there will be lack of uniformity in 
the method of attack, the experiences of one department will more than 
likely be lost on another, so that much work will be unnecessarily dupli- 
cated, and in general the results will be far from what might be attain- 



MAKING A BEGINNING 321 

able with expert supervision and, hearty cooperation from all concerned. 
With all the other conditions favorable but without such cooperation, 
the results certainly will still fall far short; and to obtain it is in itself 
no small problem. 

Enlisting Cooperation. — The conservatism and self-sufficiency of fore- 
men is first to be met and overcome. Often this can be done through 
a sincere endeavor to take them " into the game " and consult with 
them to the fullest extent. The granting of a bonus for increased 
efficiency of their departments, as indicated by increased product and 
lowered cost, is helpful. Above all, frankness with them, and the in- 
culcation of a spirit of enthusiastic loyalty throughout the previously 
existing relation between them and the management, will have smoothed 
the way completely. This is not a treatise on shop management, in 
the accepted sense; but it seems worth while to remark that the value 
of personal loyalty to a business, of real interest in it on the part of not 
only the supervisory force, but of all employees, is a most valuable 
asset — ■ and unfortunately one to the conservation and development 
of which little attention seems generally to be paid. 

The Workman an Important Factor. — While on the whole workmen 
are somewhat suspicious of efforts on the part of a management to 
enhance their productive capacity and the individual output, this atti- 
tude is much less in evidence in a plant where such a policy prevails 
as that just mentioned — that of frank and square dealing with em- 
ployees, comprehending among other things a disposition to take the 
workmen into partnership, so to speak, and give them an opportunity 
to profit by increased exertion rather than to " cut the whole hog" 
through a piece-work wage system which fixes a maximum wage for 
•every job and keeps for the management every advantage arising from 
increased efficiency and effort. In short, no greater mistake could be 
made, at the very beginning, than to overlook the workman who is to 
use the new tools. He must in the nature of the case exert greater 
activity and work at higher tension, and is justly entitled to a share of 
the profits If no such spirit of cooperation has previously been culti- 
vated, the inauguration of a high speed tool regime will be an excellent 
time and method for introducing also some method of wage payment 
which shall permit the workman to share in the profits involved in 
higher efficiency and increased energy. Unless some such provision be 
made, assuredly the attempt on the part of the management to monop- 
olize the advantages will properly be resented, and in consequence the 
returns will be materially cut down below what they might be. 

Furthermore, to insure permanent good feeling and continued high 
efficiency, it is necessary that such increment in the workman's reward 
shall be permanent. The policy in vogue in most piece-work shops of 
granting a slight increase for greater effort, only to make a reduction 



322 HIGH-SPEED STEEL 

later, when the newness of the thing has worn off, a reduction putting 
the workman on the same level of reward as before but with harder 
work to do, is as shortsighted as it is greedy; and it inevitably brings 
its own punishment — only the management generally is too obtuse 
to know it, even when it is a continuous occurrence. Losses are none 
the less large because incurred in ways intangible or unobserved. 

Tool Problem First Considered. — In a shop where no systematic effort 
has been made to take large advantage of high-speed tools, it is well to 
make a start by inquiring into the facilities for tool making and main- 
tenance (grinding included), and the extent to which tools will have 
to be bought outside. Naturally this will depend very largely upon the 
nature of the plant and the number of tools used. If very many, it will 
pay to organize a tool-making department, or to reorganize an existing 
one to fit the new conditions, and to secure the service of one or more 
expert workers with high-speed steel, according to the needs. The 
equipment necessary, and the methods involved in tool making, are 
described in the chapters dealing with that subject. In smaller estab- 
lishments it will be simplest, and probably because it would be inex- 
pedient to provide a suitable tool-making equipment and to man it with 
expert service it will be safest also, to buy tools made to specification. 
Whatever may be decided upon with reference to this point, it will be 
very necessary to provide adequate and dependable facilities for grind- 
ing the tools, in order to keep them in proper working condition. Neglect 
of this point (see chapter on Grinding) will exact the penalty in reduced 
efficiency and lowered returns. If for any reason hand grinding is neces- 
sary, in spite of the higher cost compared with machine grinding utiliz- 
ing relatively unskilled labor, it must be carefully done by skilled hands 
working as closely as possible by this method to standardized shapes 
and angles. 

Capabilities of the Equipment. — Also, whatever the conditions prevail- 
ing in the shop, it is very important that a careful inquiry be made into 
the extent and nature of the equipment, and a full report made upon 
each machine. This should show its kind and type; its capacity; limita- 
tions as to speed, traverse or feed, and cut; kind of work for which it is 
adapted and the kind for which it can be adapted; if capable of strengthen- 
ing or remodeling for higher duty and to what extent and at what probable 
cost; the kind and probable cost of a machine of maximum capabil- 
ities to take its place; and such other data as may be found to have a 
bearing on the problem in hand. With these data in hand the questions 
as to the routing and placing of jobs under the new conditions will be 
much simplified, and the purchase of new machines, when this shall 
become necessary and expedient, can be made, intelligently; without 
them the re-routing which may be necessary to insure the best results 
possible without purchasing a new machine, or the purchase of it if that 



MAKING A BEGINNING 323 

be feasible, becomes more or less guesswork. And guesswork, of all 
things, is studiously to be avoided if results are to count. 

Ill Advised and Unfortunate Experiences. — A word may not be out of 
place here in reference to certain ill advised attempts to use high-speed 
tools and machines. It happens not infrequently that the management 
of a shop becomes acquainted with the advantages obtainable through 
these, and, relying upon there presentations and guarantees of steel and 
machine makers, purchases a supply of steel and installs the machine — 
only to make a signal failure in respect of realizing expectations. The 
unfortunate result, in such case, of course is not attributable to either 
steel or machine, but to their unintelligent use under conditions which 
would preclude the attainment of satisfactory results. 

Attacking a Specific Problem. — Assuming that all preliminaries are 
arranged, so far as can be anticipated, it is in order to take up the con- 
sideration of particular jobs which may first be changed over. Evidently 
it will be desirable to take up immediately those cases where the work 
is especially trying upon the tools in use; and because of the relative 
simplicity of the tools and conditions, preferably turning operations. 
Concretely, suppose the turning of a light, high carbon shaft, requiring 
a long cut, be considered. The first point to determine is that of the tool 
to use. Only a moderately good finish being required, a standard round- 
nose tool will fit the case; and since the material is high carbon, the 
standard tool for this class of work (clearance 6 degrees, back slope 
8 degrees, and side slope 14 degrees, making the lip angle 68 degrees — 
see chapter on Design of Tools), f-inch shank, is selected. The incli- 
nation to use tool holder stock with a view to economizing in the tool 
cost is best resisted, though it may possibly be found later that a com- 
posite tool is permissible. By reference to a table of standard feeds, 
cuts and speeds, it is seen that with this tool working on this kind of 
steel at the required depth of cut (for the particular operation here 
considered, ^ inch), the maximum speed under Taylor standard con- 
ditions, according as the feed is £%, ^, T \, or -£% inch, is 110, 73.4, 49.3, 
or 39 feet per minute. By actual trial it is found that a feed of 3 * 2 inch 
per revolution will leave a finish sufficiently good to pass inspection; 
and this is therefore selected as the standard feed for the operation. 
The maximum speed then permissible, if the tool is to last 1J hours 
per grinding, is 73.4 feet per minute. Summarizing, we have speed, 
73.4 feet per minute, feed ^ inch per revolution, depth of cut ff 3 2 inch. 

Limitations Found and Changes Made. — Consulting the report on the 
machines employed (two) on the operation, it is seen that these are 
incapable of running at so high a speed, mainly because they are some- 
what worn and consume too much power in overcoming the friction 
of the machine itself when driven so rapidly. A study of the situation 
and consultation of the reports for other machines shows that an exchange 



324 



HIGH-SPEED STEEL 



can be made whereby a pair of other lathes become available without 
disadvantageously affecting the routing of the piece, which lathes are 
capable of running at the required speed. This latter, however, is not 
attainable under the existing conditions. The nearest available speeds 
are 88 and 60 feet per minute. It then becomes necessary to change 
the countershaft pulley or the driving cone, or both, to get the required 
speed; and in making the change the belt and the belt faces are widened 



TOOL TEST NO. 
NO.- 



OPERATION- 



PIECE 



MATERIAL- _ 

MACHINES OK 
SPINDLES 
OPERATED " 



CONDITION- 
LUBRICANT, 



Record of Grinds 


No. 


Mill. 

per 

Grind 


Pieces 
Finish d 


No. 


Min. 

per 

Grind 


Pieces 
Finish'd 


No. 


Min. 

per 

Grind 


Pieces 
Finish'd 


1 






16 






31 






2 






17 






32 






3 






18 






33 






4 






1!) 






34 






5 






20 






35 






6 






21 






36 






7 






22 






37 






8 






23 






38 






i) 






24 






39 






10 






25 






40 






11 






26 






41 






12 






27 






42 






13 






28 


* 




43 






14 






29 






44 






15 






30 






45 






Total 






Total 






Total 






Production Record 


Day 


Finish'd 


Scrap'd 


Day 


Finish'd 


Scrap'd 


Day 


Finish'd 


Scrap'd 




































































Total 









Date,_ 



Foreman 
Department . . 



Fig. 269. Tool test record form. Filled in mostly by the workman, or by the one conducting the test. 
It is convenient to indicate different tool steels by differently colored cards. Comments made on 
back of card. 

so as to give a sufficient margin over what would be required to pull the 
expected load. Result, a peripheral speed of 71 feet for the shaft to be 
turned. The feed mechanism is found sufficiently strong for the work 
required. The tail center is replaced with one of high-speed steel, and 
the bent-tail dogs previously used, with a quick-acting chuck. And the 
running test is begun. 

Practicable Conditions Established.— It transpires that a back rest is 
required, and that the speed 71 feet per minute, in spite of the rest and 



MAKING A BEGINNING 



325 



of the preliminary report, is so high for these machines that the vibra- 
tion set up does not permit sufficient accuracy in the work and also 
effects a reduction in the time after which the tool must be ground; 
hence it becomes necessary to reduce the speed or to install new ma- 
chines. The latter course being for the present inexpedient, the cutting 



TOOL TEST NO 

jeiECE OPERATION-. 

MATERIAL CONDITION 

T.OOL__ „ SIZE 



ANNUAL REQUIREMENT _ 






PIECES 


Tool Number 


No 


No 


Gain 


Speed, (Feet per minute ) 
Eeed, (Inches per Revolution) 














Cut. (Depth) 








{ipm'aTell °P erated 
Cutting Timej (per Piece) 














Grinding Time, •• <• 








Time Allowance " ■ 








Actual Time for Operation, 








Daily Output 








Rate per Hundred Pieces 








Cost of Tool " " 








Cost of Power « » 








Interest & Depreciation Hundred Pieces 








Overhead Expense " >« 








Cost of Scrap " " 








Total " " 









Saving on Year's Requirement . 



( Machines > 
, } A 

' Spindles > 

Daily Wages of Workman — Former,. 



Days 



;New, 



Duration of Test, 

New Rate in Effect, 

Date._^ 



..Department 



Fig. 



270. Record of data and results. Cost of power, depreciation and interest, and overhead expense 
are rarely of sufficient importance to require consideration. Remarks made on back of card. 



speed is reduced to 58 feet per minute (provision having previously been 
made for such a contingency) and the result is found to be all that could 
be desired in respect of finish, while the tool endurance rather more than 
equals that anticipated. It remains then to calculate the economy 
effected and to rearrange the labor cost accordingly — not forgetting to 
take the workman into account, as already pointed out. 

Data Determined. — From the factory records it is found that the 
yearly requirement is 24,000 pieces; average daily output (two lathes), 
92 pieces; piecework rate, $2,125 per hundred; average daily wage for 



326 



HIGH-SPEED STEEL 



workman, $1.91. Also, determined either from records or observation 
with stop watch, as the case may be: actual cutting time, per piece, 
8 minutes; time allowance for grinding and setting tool, average, 1 min- 
ute per piece; time allowance for handling piece, cleaning machine, and 
other losses, 4 minutes: or a total time allowance of 5 minutes, and a 
total operation time of 13 minutes per piece. The actual operation 



INSTRUCTION CARD. 



Piece No.. 
Operation - 



-Department . 
-Order No 



Fixtures ) 
Jigs J 



Finish 
Gauge 



-Machines 



Tool to use- 



Cutting speed- 



Revolution of 



Table feed : 
Traverse 



tool 



-feet per minute 
per minute 



-feet per minute = 



-per 



stroke 
revolution 



Depth of cut- 



Change tool every- 



-minutes 



Lubricant or cooling agent- 



Expected daily output- 



Directions: 



Date- 



-Signed- 



Fig. 271. Card of instructions sent to workman with new tool when job is 
changed over. 

time is half this, or 6J minutes, since two lathes are used and two pieces 
are finished during each period of 13 minutes. 

The data observed (or computed beforehand, if the supervisory force 
has sufficient skill and experience to determine this without recourse to 



MAKING A BEGINNING 327 

experiment) bring out that the actual cutting time under the new con- 
ditions is 4.5 minutes; time for changing tools, etc., 0.2 minutes; time 
for handling and changing piece, 2.5 minutes; or a total time of 7.2 
minutes per piece. But since two lathes are used, the real time per 
piece becomes one half this, or 3.6 minutes; and the daily (10 hour) 
output is about 160 pieces, or an increase of rather more than 75 per cent. 
On a piecework basis, allowing the workman a substantial increase in 
pay (suppose we say a day rate approximating $2.30, as against his 
former $1.91) because of this greater exertion, the cost of the job can well 
be reduced to $1.40 per hundred, effecting a saving $0,725 per hundred 
pieces, which in a day amounts to nearly $1.50, or an economy of more 
than $220 on the year's requirement. Under a good premium or bonus 
wage system even this showing would be bettered. 

The Element of Tool Cost. — This item, however, is by no means the 
only one through which economies are effected. There is, for example, 
the matter of tool cost. In most cases it might perhaps be expected that 
this item would be increased. As a matter of fact it rarely is so, because 
of the greater life of a high-speed tool and the consequent distribution 
of its first cost over a greatly increased output. In this particular job 
it turns out that there is a saving in tool cost approximating $0.08 per 
hundred pieces, or not far from $20.00 for the year's requirement. This 
does not include tool maintenance and grinding, in which item there 
would be another considerable saving, since this job was very hard upon 
carbon and self-hardening tools. There is also the matter of the largely 
increased time during which these standard machines become available 
for other work. Whereas before the change two lathes were required 
practically the whole working year (about 260 days) to get out the re- 
quirement, under the new conditions they are required for a maximum 
of only 150 days, leaving them available for about half the time for other 
work and consequently reducing capital and maintenance account by 
nearly one half. 

Saving in Scrap. — Furthermore, in this job the scrap loss was pre- 
viously an important factor — almost half as great, indeed, as the labor 
cost; and this is reduced, if not to a negligible item, at any rate to 
a reasonable minimum for the job. The saving through this item is 
shown, along with others, in the following table. 

Data Summarized. — Quite evidently this is not a typical factory job. 
Nevertheless it is representative of a distinct class of operations to be 
found in most plants; and it has been selected as an example in order to 
indicate as clearly as possible the factors to be considered in changing 
over jobs from ordinary to high-speed tools. About the same points 
are involved in almost any other operation of the kind with which we 
are at present concerned, and the method of attack will be about the 
same. 



328 



HIGH-SPEED STEEL 

TABLE X. 



Item (per 100 Pieces). 


Self-hard- 
ening Tool. 


High-Speed 
Tool and 
Equipment. 


Economy Ef- 
fected . 


Total, on 
Year's Re- 
quirement. 


Piecework rate 


$2,125 
0.089 
0.072 
1.050 


$1,400 
0.004 
0.041 
0.160 


$0,725 
0.085 
0.031 
0.890 


$174.00 

20.40 

7.44 

213.60 


Tool cost (including sharp 'ng) 
Insurance and interest, equip't 
Scrap, net loss 
























Totals 


$3,336 


$1,605 


$1,731 


$415.44 



1 Neglected. 

Classification of Jobs. — So-called " try-outs " are useful in connection 
with the first introduction of high-speed tools, and perhaps are neces- 
sary; though the method, the time, and the order of doing the work can 
almost, if not quite as well, be determined in the office and prescribed 
for the workman without actual test, where a proper knowledge of the 
conditions exist. In fact it would be quite out of the question to under- 
take a test or to make a try-out of every one of the tens of thousands of 
operations in a big plant. It is enough that this be done, if at all, in a 
relatively few cases which are selected as typical of most those met with. 
All jobs are then classified according to their characteristic features, and 
standards established for the several classes. Evidently the analysis 
of a great number of very different jobs will present manifold difficulties, 
and some will seem to defy classification. It is imperative, however, 
that this be done so far as possible in order to minimize the time required 
for making changes and calculations. There must of course be some 
rational basis for such a grouping of jobs, though this may vary more 
or less according to local conditions and the specific nature of most of 
the operations. The factors here indicated are of sufficient importance 
to require consideration, and may be taken tentatively, at least, as a 
basis : 

a |TyP e °f machine on which job is done. 
[Limitations and capabilities of machine available. 

(Material worked upon, and its particular qualities. 
Shape and other special characteristics of the piece operated 
upon, including size. 
Kind of tool to be used, and its capabilities. 
„ Amount of material to be removed. 
' Possibility of using multiple tools. 
Feasibility of lubricating or cooling tool or work. 
D. Finish required. 



MAKING A BEGINNING 329 

Other elements of course enter into many jobs; very likely in not a 
few instances they may assume importance beyond some or perhaps 
even all those here pointed out. This, however, is unlikely to be so, 
and these may safely be taken as fundamental to the determination of 
standards for operations except as special cases may arise. The standards 
once established, it should be possible to fit any given job nearly enough 
to a pretty clearly defined class, and to modify the conditions later as 
occasion or experience may indicate. 



APPENDIX A. 

ANALYSES OF HIGH-SPEED AND SPECIAL STEELS OF 
VARIOUS MAKES. 



02 


S 

3 

■3 

03 
C 

> 


B 

3 
C 
0) 

.a 

O 
i=5 


a 

c 

3 

H 


a 

3 

a 

o 

5 


c 
o 

.o 

u 
03 


0) 

o 

a 

oj 

bo 

c 

03 
<=; 


c 
o 
._o 

in 


W 

o 
o 


3 
- 02 


1 

la 

2 

3 

4 

5 

6 

7 

8 

9 

10 
11 
12 
13 
14 
15 
16 
17 
18 
19 
20 
21 
22 
23 
24 
25 
26 
26a 
26b 
27 
28 
29 
30 
31 
32 
33 
34 
35 
36 
37 
38 
39 
40 
41 
42 
43 
44 
45 
46 
47 
48 
49 


0.32 
0.29 




17.81 
18.19 
16.19 
14.41 
17.61 
14.23 
25.45 
14.91 
17.79 
19.64 
18.99 
23.28 
18.93 
13.44 
24.64 
19.97 
19.16 
9.25 
16.00 
16.00 
14.71 
15.31 
14.91 
14.62 


5.95 
5.47 
3.86 
3.28 
4.24 
3.44 
2.23 
5.71 
2.84 
2.85 
2.61 
2.80 
3.52 
3.04 
7.02 
3.88 
5.61 
6.11 
3.50 
3.50 
2.90 
2.88 
2.80 
2.81 
4.30 
3.67 
2.95 
2.85 
2.93 
2.70 
4.10 
2.69 
2.90 
5.11 
6.00 
4.58 


0.682 
0.674 
0.736 
0.709 
0.502 
0.739 
0.838 
0.790 
0.650 
0.760 
0.670 
0.800 
0.580 
0.760 
0.600 
1.280 
0.790 
0.320 
0.700 
0.700 
0.700 
0.540 
0.450 
0.600 
0.900 
1.160 
0.705 
0.791 
0.800 
0.250 
0.370 
0.640 
0.750 
0.490 
0.650 
0.560 
0.650 
0.620 
0.440 
0.550 
0.550 
0.660 
0.790 
0.660 
0.320 
0.400 
0.540 
0.500 
0.940 
1.030 
1.190 
1.250 


0.07 
0.11 
0.06 
0.07 
0.10 
0.06 
0.29 
0.06 
0.12 
0.30 
0.20 
0.11 
0.19 
0.09 
0.03 
0.14 


0.049 
0.043 
0.210 
0.120 
0.240 
0.165 
0.034 
0.060 
0.087 
0.090 
0.265 
0.165 
0.125 
0.052 
0.205 
0.220 
























































0.48 


0.013 


0.012 






0.014 
0.015 
0.029 


0.009 
0.009 
0.016 








2.03 

4.21 






















0.28 


7.60 


0.13 


0.081 






















0.12 
0.12 
0.10 
0.18 
0.12 
0.10 
0.01 


0.196 
0.133 
0.090 
0.320 
0.481 
1.340 


0.017 
0.018 
0.018 
0.017 
0.016 
0.024 
0.013 


0.010 
0.009 
0.008 
0.009 
0.008 
0.008 
0.008 








0.75 




6.25 


10.68 
14.91 
14.29 
13.40 
17.27 
16.48 
18.66 
14.83 
17.60 
19.00 
16.75 
















0.06 

0.18 
0.24 
0.08 




0.020 
0.035 
0.014 
0.012 
0.020 
0.010 
0.018 
0.020 
0.016 
0.020 
0.017 
0.016 


0.008 






0.179 
0.090 
0.393 






0.008 
0.014 
0.010 
0.007 
0.019 
0.007 
0.006 
0.010 
0.010 
0.010 








5.19 








0.10 
0.17 
0.20 


0.200 
0.110 
0.038 




0.78 
9.61 


13.00 

17.54 

19.09 

17.81 

19.03 

14.27 

18.40 

15.29 

16.22 

10.08 

13.76 

4.78 

0.46 

7.56 

2.25 


2.88 
2.72 
2.69 
2.48 

3.55 
2.89 
1.85 
4.73 
3.00 
4.49 
0.69 
0.00 
3.34 
0.28 






0.12 
0.27 
0.11 

0.08 
0.12 
0.15 
0.18 
0.16 
0.07 
0.27 
0.30 
0.46 
0.85 


0.100 
0.070 
0.090 
0.036 
0.150 
0.135 
0.340 
0.120 














0.015 
0.028 
0.010 
0.019 
0.025 








0.008 
0.008 
0.006 
0.008 
















4.38 
0.34 


0.210 
0.110 
0.118 
0.200 
0.210 


0.015 
0.010 
0.025 
0.024 


0.005 
0.010 
0.009 
0.025 























330 



APPENDIX 331 

MEMORANDA. 

Analyses numbered from 1 to 25 inclusive are those given by Taylor. 
1 and la are the same steel, the one referred to by him as the best of all 
those used in the Taylor- White experiments. 

44 is the average of the analyses of 12 different melts of the same 
steel, or rather of steel marketed under the same name. 

45 is high-speed, but not of the highest grade. 

46, 47 and 48 are steels recently put upon the market as " semi- 
high-speed " or " intermediate " steels. 

49 is sold as a steel especially adapted to finishing cuts. It is not at 
all in the high-speed class. 



APPENDIX B. 

FRED W. TAYLOR ON THE VARIOUS METHODS OF HARD- 
ENING HIGH SPEED STEEL TOOLS. ' 

Special Treatments Unnecessary. — For some years past it has been 
rather amusing to us to hear the special directions given by the various 
manufacturers of steel suitable in chemical composition for making the 
high-speed tools. Very frequently a tool steel maker implies, or directly 
states, that the chemical composition of his particular high speed tool 
steel requires " special treatment." The fact is, however, that our 
recent experiments demonstrate beyond question the fact that no 
other method which has come to our attention produces a tool superior 
in red hardness {i.e., high speed cutting ability), or equal in uniformity 
to the method described. This applies to all makes of high speed tool 
steels which are capable of making first-class tools, whatever their 
chemical composition. 

Various Methods Tried. — It is the writer's belief that during our long 
series of experiments at the Bethlehem Steel Company, in our search 
for uniform tools and for the method of imparting the highest degree 
of red hardness to tools, we tried substantially every method which has 
since come to our attention. 

For instance, in giving the tools the high heat we heated them in a 
blacksmith's coke fire, a blacksmith's soft-coal fire, in muffles over a 
blacksmith's fire, and in gas-heated muffles. We also constructed 
various furnaces for this purpose. We heated tools by means of an 
electric current, with noses under water, and out of water, and by im- 
mersion in molten cast iron. Moreover, by every one of these methods 
we were able to produce a first-class tool, provided only the tool was 
heated close to the melting point. 

Cooling Experiments. — In cooling from the high heat we experi- 
mented with a large variety of methods. After being heated close to 
the melting point, tools were immediately buried in lime, in powdered 
charcoal, and in a mixture of lime and powdered charcoal; thus they 

1 The extensive investigations, and prodigious amount of time and labor devoted 
to them in the development of high-speed steels and their treatment, give to the follow- 
ing extract from Mr. Taylor's address or report a special significance. The para- 
graphs are 1001 to 1006 inclusive, at pages 200 and 201 of the address "The Art of 
Cutting Metals," already mentioned. 

332 



APPENDIX 333 

were cooled extremely slowly, hours being required for them to get 
below a red heat. And we wish clearly to state the fact that tools 
cooled even as slowly as this, while "they were in many cases quite soft 
and could be filed readily, nevertheless maintained the property of 
" red hardness " in as high a degree as the very best tools, and were 
capable of cutting the medium and softer steels at as high cutting speeds 
as the best tools which were cooled more rapidly and which were much 
harder in the ordinary sense. 

Tools were also cooled from the high heat in a muffle or slow cooling 
furnace with a similar result. On the other hand, we made excellent 
high-speed tools by plunging them directly into cold water from the 
high heat, and allowing them to become as cold as the water before re- 
moving them. Between these two extremes of slow and fast cooling; 
cooling in lime, charcoal, or a muffle, on the one hand, and in cold water 
on the other; other cooling experiments covering a wide range were 
conducted. We tried cooling them partly in water and then slowly 
for the rest of the time; partly in oil, and then slowly for the rest of the 
time; partly by a heavy blast of air from an ordinary blower and the 
rest of the time slowly; partly under a blast of compressed air and then 
slowly. We also reversed these operations by cooling first slowly and 
then fast, as described. We also cooled them entirely in an air blast 
and entirely in oil, and then partly first in oil, afterward in water, and 
then first in water and afterward in oil. 

Good Tools by all Methods. — By every one of these methods we were 
able to make a good high-speed tool; i.e., a tool having a large degree 
of red hardness, and capable of cutting at very high cutting speeds. 
But by none of these processes were we able to obtain tools as uniform 
and regular as those produced by our lead bath and air cooling. 



APPENDIX C. 

REFERENCE TABLE FOR DETERMINING CUTTING SPEEDS. 



Feet per 
Minute. 


5 


10 


15 


20 


25 


30 


35 


40 


45 


50 


Diam. 
in Inches. 


REVOLUTIONS PER MINUTE. 


i 

2 


38.2 


76.4 


114.6 


152.9 


191.1 


229.3 


267.5 


305.7 


344.0 


382.2 


1 


30.6 


61.2 


91.8 


122.5 


153.1 


183.7 


214.3 


244.9 


275.5 


306.1 


f 


25.4 


50.8 


76.3 


101.7 


127.1 


152.5 


178.0 


203.4 


228.8 


254.2 


i 


21.8 


43.6 


65.5 


87.3 


109.1 


130.9 


152.7 


174.5 


196.3 


218.9 




19.1 


38.2 


57.3 


76.4 


95.5 


114.6 


133.8 


152.9 


172.0 


191.1 


n 


17.0 


34.0 


51.0 


68.0 


85.0 


102.0 


119.0 


136.0 


153.0 


170.0 




15.3 


30.6 


45.8 


61.2 


76.3 


91.8 


106.9 


122.5 


137.4 


153.1 


if 


13.9 


27.8 


41.7 


55.6 


69.5 


83.3 


97.2 


111.1 


125.0 


138.9 


ii 


12.7 


25.4 


38.2 


50.8 


63.7 


76.3 


89.2 


101.7 


114.6 


127.1 


if 


11.8 


23.5 


35.0 


47.0 


58.9 


70.5 


82.2 


93.9 


105.7 


117.4 


if 


10.9 


21.8 


32.7 


43.6 


54.5 


65.5 


76.4 


87.3 


98.2 


109.1 


if 


10.2 


20.4 


30.6 


40.7 


50.9 


61.1 


71.3 


81.5 


91.9 


101.9 


2 


9.6 


19.1 


28.7 


38.2 


47.8 


57.3 


66.9 


76.4 


86.5 


95.5 


21 


8.5 


17.0 


25.4 


34.0 


42.4 


51.0 


59.4 


68.0 


76.2 


85.0 


21 


7.6 


15.3 


22.9 


30.6 


38.2 


45.8 


53.5 


61.2 


68.8 


76.3 


2f 


6.9 


13.9 


20.8 


27.8 


34.7 


41.7 


48.6 


55.6 


62.5 


69.5 


3 


6.4 


12.7 


19.1 


25.5 


31.8 


38.2 


44.6 


51.0 


57.3 


63.7 


31 


5.5 


10.9 


16.4 


21.8 


27.3 


32.7 


38.2 


43.6 


49.1 


54.5 


4 


4.8 


9.6 


14.3 


19.1 


23.9 


28.7 


33.4 


38.2 


43.0 


47.8 


41 


4.2 


8.5 


12.7 


16.9 


21.2 


25.4 


29.6 


34.0 


3?.l 


42.4 


5 


3.8 


7.6 


11.5 


15.3 


19.1 


22.9 


26.7 


30.6 


34.4 


38.2 


51 


3.5 


6.9 


10.4 


13.9 


17.4 


20.8 


24.3 


27.8 


31.3 


34.7 


6 


3.2 


6.4 


9.6 


12.7 


15.9 


19.1 


22.3 


25.5 


28.7 


31.8 


7 


2.7 


5.5 


8.1 


10.9 


13.6 


16.4 


19.1 


21.8 


24.6 


27.3 


8 


2.4 


4.8 


7.2 


9.6 


11.9 


14.3 


16.7 


19.1 


21.1 


23.9 


9 


2.1 


4.2 


6.4 


8.5 


10.6 


12.7 


14.9 


17.0 


19.1 


21.2 


10 


1.9 


3.8 


5.7 


7.6 


9.6 


11.5 


13.4 


15.3 


17.2 


19.1 


11 


1.7 


3.5 


5.2 


6.9 


8.7 


10.4 


12.2 


13.9 


15.6 


17.4 


12 


1.6 


3.2 


4.8 


6.4 


8.0 


9.6 


11.1 


12.7 


14.3 


15.9 


13 


1.5 


2.9 


4.4 


5.9 


7.3 


8.8 


10.3 


11.8 


13.2 


14.7 


14 


1.4 


2.7 


4.1 


5.5 


6.8 


8.1 


9.6 


10.9 


12.3 


13.6 


15 


1.3 


2.5 


3.8 


5.1 


6.4 


7.6 


8.9 


10.2 


11.5 


12.7 


16 


1.2 


2.4 


3.6 


4.8 


6.0 


7.2 


8.4 


9.6 


10.7 


11.9 


17 


1.1 


2.2 


3.4 


4.6 


5.6 


6.7 


7.9 


9.0 


10.1 


11.2 


18 


1.1 


2.1 


3.2 


4.2 


5.3 


6.4 


7.4 


8.5 


9.6 


10.6 


19 


1.0 


2.0 


3.0 


4.0 


5.0 


6.0 


7.0 


8.0 


9.1 


10.1 


20 


1.0 


1.9 


2.9 


3.8 


4.8 


5.7 


6.7 


7.6 


8.6 


9.6 


21 


.9 


1.8 


2.7 


3.6 


4.5 


5.5 


6.4 


7.3 


8.1 


9.1 


22 


.9 


1.7 


2.6 


3.5 


4.3 


5.2 


6.1 


6.9 


7.8 


8.7 


23 


.8 


1.7 


2.5 


3.3 


4.1 


5.0 


5.8 


6.6 


• 7.5 


8.3 


24 


.8 


1.6 


2.4 


3.2 


4.0 


4.8 


5.6 


6.4 


7.2 


8.0 


25 


.8 


1.5 


2.3 


3.1 


3.8 


4.6 


5.3 


6.1 


6.9 


7.6 


26 


.7 


1.5 


2.2 


2.9 


3.7 


4.4 


5.1 


5.9 


6.6 


7.3 


27 


.7 


1.4 


2.1 


2.8 


3.5 


4.2 


5.0 


5.7 


6.4 


7.1 


28 


.7 


1.4 


2.0 


2.7 


3.4 


4.1 


4.8 


5.5 


6.1 


6.8 


29 


.7 


1.3 


2.0 


2.6 


3.3 


4.0 


4.6 


5.3 


5.9 


6.6 


30 


.6 


1.3 


1.9 


2.5 


3.2 


3.8 


4.5 


5.1 


5.7 


6.4 



334 



APPENDIX 335 

The revolutions per minute for any greater speed may be obtained 
by multiplication and addition. Suppose it is desired to find the r.p.m. 
of a milling cutter having a diameter of \\ inches and expected to run 
at a peripheral speed of 85 feet per minute. The required number may 
be found by following the line opposite the given diameter, 4J, to the 
column under 40, where is found the number 34.0; and also to the 
column under 45, where is found the number 38.1. Adding these numbers 
we have the required r.p.m. for a speed of 40 -f 45, or 85 feet per minute, 
which is 72.1. If the r.p.m. for a surface speed of, say 120 feet, is re- 
quired, it may be found by multiplying the number in the column under 
20 by 6, which in the case of a 2f inch cutter would be 27.8 X 6 or 166.8. 

Conversely, the surface speed required for a given diameter and r.p.m. 
can be determined, though for this the use of the following formula is 
simpler: S = D X R X .2618, in which S is the surface speed in feet 
per minute, D the diameter, and R the revolutions per minute. We also 
have: 

R X .2618 
S 



336 



APPENDIX 



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a^uaicu J9d iiaaj n.; peadg 



APPENDIX 



337 



As shown in the enlarged section, follow the vertical line representing 
the given diameter to its intersection with the horizontal line correspond- 
ing to the required surface speed; follow the diagonal nearest this point 



3 Diameter 



4 

w 



„1 min. 35 sec. to turn one inch 



Fig. 273. Enlarged section of Fig. 272, showing method of determining time of operation. 

up or down, until it meets the horizontal line corresponding to the desired 
feed as read from the left of the table. A vertical line dropped from this 
point to the bottom line will there show the time in minutes it will take 
to turn one inch under the given conditions. Diagram by A. Thompson, 
re-published by courtesy of Machinery, New York. 



S38 



APPENDIX 



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« 

c ° 

7 a 

_ a 

S 'x 
.2 S 

■- S 

■6 a 

a -a 

^^ 
o o 
bO O 

1 s 

x -^ 

t, G 

&, 
o 
^3 

03 

CD 

03 

a 



« 




APPENDIX F. 

PRACTICAL TABLE OF 
CUTTING SPEEDS: STANDARD !■" TOOL. 



Depth of 
Cut in 
Inches. 


Feed in 
Inches. 


Cutting Speed in Feet per Minute for a Tool which is to Last 1 Hour and 
30 Minutes before Re-grinding. 


Soft Cast 
Iron. 


Medium 
Cast Iron. 


Hard Cast 
Iron. 


Soft Steel. 


Medium Steel. 


Hard Steel. 


3 
32 


i 

64 

i 

32 

1 

3 
32 

1 
f 

3 
T6 


239 

191 
142 
118 
103 
85.0 


119.6 
95.3 
70.8 
59.1 
51.7 
42.5 


69.8 
55.6 
41.3 
34.4 
30.2 
24.8 


518 
366 
257 
209 


259 

183 
129 
105 


118 
83.2 
58.4 
47.5 








1 
8 


1 
64 

1 
Wl 

1 

vs 

3 

32 
1 
8 
3 
. 16 


216 
172 
128 
107 

93.4 

76.8 


108 
86.2 
64.0 
53.4 
46.7 
38.4 


63.1 
50.3 
37.3 
31.2 
27.3 
22.4 


450 
317 
223 
182 
157 


225 

158 

112 
90.8 
78.5 


102 
72.0 
50.7 
41.4 
35.7 


3 
16 


1 
64 

1 
32" 

1 
TE 

3 
32 

1 

"8" 

3 
16 


187 

149 

111 
92.5 
73.1 
66.4 


93.5 
74.6 
55.5 
46.3 
36.5 
33.2 


54.6 
43.6 
32.7 
27.0 
21.3 
19.4 


370 
260 
183 
149 
129 
105 


185 

130 
91.7 
74.6 
64.5 
52.6 


84.1 
59.1 
41.6 
33.8 
29.3 
23.8 


1 
4 


1 
64 

1 
32 

1 
T6" 

3 
32" 

1 

S 

3 
16 


168 

134 
99.8 
83.2 
72.6 
59.7 


84.1 
67.2 
49.9 
41.6 
36.3 
29.8 


49.1 
39.2 
29.1 
24.3 
21.2 
17.4 


322 
227 
159 
130 
112 
91.4 


161 

113 
79.7 
65.0 
56.1 
45.7 


73.2 
51.6 
36.1 
29.5 
25.5 
20.8 


3 

8 


1 
64 

1 
SI 

1 
TS 

3 

wz 

1 

8 
3 


144 

115 
85.1 
70.9 
62.0 
51.0 


71.8 
57.3 
42.6 
35.5 
31.0 
25.5 


41.9 
33.4 
24.8 
20.7 
18.1 
14.9 


264 
186 
131 
107 
92.2 


132 
93.1 
65.5 
53.4 
46.1 


60.0 
42.3 
29.8 
24.1 
20.8 


1 
2 


1 
64 

1 
32 

1 

h 

1 
~S 
3 


131 

105 
77.6 
64.7 
56.6 
46.5 


55.6 
52.3 
38.8 
32.4 
28.3 
23.3 


38.3 
30.5 
22.7 
18.9 
16.5 
13.6 


230 

162 

114 

' 92.6 


115 
80.9 
56.9 
46.3 


52.3 
36.8 
25.9 
21.0 








3 

4 


1 
64 

1 
S2 

1 

_3_ 
32 

* 

3 

16 


112 
89.2 
66.2 
55.2 
48.3 
39.7 


56.0 
44.6 
33.1 
27.6 
24.2 
19.8 


32.7 
26.0 
19.3 
16.1 
14.1 
11.6 








































1 



339 



340 



APPENDIX 




PRACTICAL TABLE OF 
CUTTING SPEEDS : STANDARD 1" TOOL. 







Cutting Speed in Feet 


per Minute for a Tool which is to Last 1 Hour and 


Depth of 






30 Minutes before Re-grinding. 




Cut in 
Inches. 


Inches. 


Soft Cast. 
Iron. ' 


Medium 
Cast Iron. 


Hard Cast 
Iron. 


Soft Steel. 


Medium Steel. 


Hard Steel. 




i 


226 


113 


66.0 


490 


245 


Ill 


3 
32 


i 


177 


88.4 


51.6 


339 


169 


77.0 


i 


130 


64.8 


37.8 


235 


117 


53.4 


3 


107 


53.5 


31.2 


189 


94.5 


43.0 




1 
t 
3 
1 6 


92.8 
75.7 


46.4 
37.8 


27.1 
22.1 
















1 


205 


102 


59.8 


427 


214 


97.0 




1 
32 


160 


85.1 


46.8 


296 


148 


67.2 


1 


1 


118 


58.8 


34.3 


205 


102 


46.6 


8 


3 


97.0 


48.5 


23.3 


165 


83.0 


37.5 




1 
? 


84.2 


42.1 


24.6 


142 


71.0 


32.3 




3 

16 


68.6 


34.3 


20.0 










1 


181 


90.6 


52.9 


358 


179 


81.3 




1 


142 


70.8 


41.3 


247 


124 


56.1 


3 


1 


104 


51.9 


30.3 


171 


85.5 


38.8 


16 


3 
32 


85.8 


42.9 


25.0 


138 


69.0 


31.3 




x 


74.3 


37.2 


21.7 


118 


59.0 


26.8 




3 

16 


60.6 


30.3 


17.7 


95.0 


47.5 


21.6 




1 


165 


82.3 


48.1 


315 


157 


71.6 




1 
32 


129 


64.4 


37.5 


218 


109 


49.5 


1 


1 


94.3 


47.1 


27.5 


150 


75.0 


34.1 


4 


_3_ 


77.8 


38.9 


22.7 


121 


60.5 


27.5 




1 


67.5 


33.7 


19.7 


104 


52.0 


23.6 




16 


55.0 


27.5 


16.1 
















1 


143 


71.5 


41.8 


263 


132 


59.8 




1 
32 


112 


56.0 


32.6 


182 


91.0 


41.4 


3 


1 
TB" 


81.9 


41.0 


23.9 


126 


62.8 


28.5 


8 


3 


67.6 


33.8 


19.7 


101 


50.6 


23.0 




1 

3 

16 


58.6 
57.5 


29.3 

28.7 


17.1 
16.8 






















1 


132 


66.2 


38.6 


232 


116 


52.7 




1 
32 


104 


51.6 


30.2 


161 


80.5 


36.6 




1 
T6~ 


75.8 


37.9 


22.1 


111 


55.7 


25.3 


1 
2 


3 
32 

1 
f 

3 
16 


62.6 
54.2 
44.2 


31.3 
27.1 
22.1 


18.3 
15.8 
12.9 



























APPENDIX 



841 




PRACTICAL TABLE OF 
CUTTING SPEEDS: STANDARD V' TOOL. 



Depth of 
Cut in 
Inches. 


Feed in 
Inches. 


Cutting Speed in Feet per Minute for a Tool which is to Last 1 Hour and 
30 Minutes before Re-grinding. 


Soft Cast 
Iron. 


Medium 
Cast Iron. 


Hard Cast 
Iron. 


Soft Steel. 


Medium Steel. 


Hard Steel. 


3 
32 


i 

64 

i 

32 

1 

A 

\ 

3 
16 


220 

169 

122 
99.8 
86.4 
70.1 


110 
84.6 
61.2 
49.9 
43.2 
35.1 


64.2 
49.4 
35.7 
29.1 
25.2 
20.5 


476 
325 
222. 
177 


238 
162 
111 
88.4 


108 
73.8 
50.4 
40.2 














1 

8 


1 
64 

1 
3T 

1 

3 

3T 
l 
t 

3 

16 


202 

156 

112 
91.8 
79.3 
64.3 


101 
77.8 
56.2 
45.9 
39.7 
32.2 


58.9 
45.4 
32.8 
26.8 
23.2 
18.8 


420 
286 
195 
156 
133 


210 

143 
97.6 
77.9 
66,4 


95.5 
65.0 
44.4 
35.4 
30.2 


3 
16 


1 
64 

1 
32 

1 
T§ 

3 
32 

i 
3 
16 


178 

137 
99.4 
81.0 
70.1 
56.8 


89.0 
68.6 
49.7 
40.5 
35.0 
28.4 


52.0 
40.1 
29.0 
23.7 
20.5 
16.6 


352 
240 
164 
131 
112 


176 

120 
82 

65.5 
56.0 


80.0 
54.5 
37.3 
29.8 
25.5 








1 

4 


1 
64 

1 
3~2 

1 
TS 

A 
i 

3 

16 


163 

126 
90.8 
74.1 
64.1 
52.0 


81.5 
62.9 
45.4 
37.0 
32.0 
26.0 


47.7 
36.7 
26.5 
21.6 
18.7 
15.2 


312 
213 
145 
116 


156 
107 

72.6 
58.1 


70.9 
48.4 
33.0 
26.4 














3 

8 


1 
SI" 

1 
5? 

1 
T6~ 

1 
¥ 
3 
16 


144 

111 
80.0 
65.3 
56.4 
45.8 


71.8 
55.4 
40.0 
32.6 
28.2 
22.9 


41.9 
32.3 
23.4 
19.1 
16.5 
13.4 


264 
180 
122 


132 
90.2 
61.1 


60.0 
41.0 
27.8 














1 


1 
64 

1 
3T 

1 

TS 


135 

104 
75.2 
61.4 
43.1 


67.5 
52.1 
37.6 
30.7 
21.6 


39.4 
30.4 
22.0 
17.9 
12.6 


237 
162 


118 
80.8 


53.8 
36.7 








l 








' 











342 



APPENDIX 




PRACTICAL TABLE OF 
CUTTING SPEEDS: STANDARD §" TOOL. 







Cutting Speed in Feet 


per Minute for a Tool which is to Last 1 Hour and 


Depth of 
Cut in 
Inches. 


Feed in 
Inches. 






30 Minutes before Re-grinding. 




Soft Cast 


Medium 


Hard Cast 










Iron. 


Cast Iron. 


Iron. 


Soft Steel. 


Medium Steel. 


Hard Steel. 




i 

64 


222 


Ill 


65.0 


482 


241 


110 


3 
32 


h 


169 


84.3 


49.2 


323 


161 


73.4 


1 


120 


59.8 


34.9 


217 


108 


49.3 


3 

-52 


97.0 


48.5 


28.3 


172 


85.8 


39.0 




i 
3 
16 


83.4 
66.4 


41.7 
33.2 


24.4 
19.4 






















1 
64 


203 


102 


59.3 


423 


212 


96.1 




1 
3? 


156 


78.2 


45.6 


284 


142 


64.5 


1 


1 
1$ 


110 


55.0 


32.0 


190 


95.2 


43.2 


8 


A 


88.8 


44.4 


25.9 


151 


75.3 


34.2 




i 


76.2 


38.1 


22.3 


128 


63.8 


29.0 




3 

T6~ 


60.9 


30.4 


17.8 
















J_ 


181 


90.6 


52.9 


358 


179 


81.4 




A 


137 


68.5 


40.0 


240 


120 


54.5 


3 


A 


97.7 


48.9 


28.5 


161 


80.5 


36.6 


16 


3 

32 


78.0 


39.0 


22.8 


127 


63.7 


28.7 




1 

3 

16 


67.5 
54.2 


33.7 
27.1 


19.7 
15.8 






















1 


167 


83.6 


48.8 


320 


160 


72.7 




1 
35 


126 


63.2 


36.9 


215 


107 


48.8 


1 


1 


90.8 


45.4 


26.3 


144 


72 


32.7 


4 


_3_ 


72.7 


36.3 


21.2 










1 


62.7 


31.3 


18.3 
















1 


150 


75.0 


43.8 


276 


138 


62.7 




1 
32 


113 


56.7 


33.1 


185 


92.4 


42.0 


3 


1 


81.0 


40.5 


23.6 








8 


3 
32" 


65.5 


32.7 


19.1 















APPENDIX 



343 




PRACTICAL TABLE OF 
CUTTING SPEEDS: STANDARD «" TOOL. 



Depth of 
Cut in 
Inches. 


Feed in 
Inches. 


Cutting Speed in Feet per Minute for a Tool which is to Last 1 Hour and 
30 Minutes before Re-grinding. 


Soft Cast 
Iron. 


Medium 
Cast Iron. 


Hard Cast 
Iron. 


Soft Steel. 


Medium Steel. 


Hard Steel. 


1 
16 


l 

64 

1 

1 








548 
358 
235 


274 
179 
117 


125 
81.6 
53.3 

106 
69.5 
45.5 
35.5 




















3 
32 


A. 
64 

1 
32 

1 
T6~ 

A 
* 


216 

160 

110 
88.4 
75.4 


108 
80.0 
55.0 
44.2 
37.7 


63.0 
46.6 
32.2 

25.8 
22.0 


467 
306 
200 
156 


234 
153 
100 
78.0 








1 

8 


i 

6~4 

1 
32" 

1 
TB 

h 

i 


200 

148 

104 
82.6 
69.6 


100 
74.0 
51.8 
41.3 
34.8 


58.6 
43.3 
30.2 
24.1 
20.3 


417 
273 
179 
140 


209 

136 
89.3 
69.8 


94.8 
62.0 
40.6 
31.7 


3 

16 


i 

64 

1 

TB 
3 

i 


183 

135 
94.0 
75.4 
64.3 . 


91.6 
67.5 
47.0 
37.7 
32.2 


68.0 
39.4 
27.4 
22.0 

•18.8 


362 
236 
155 


181 
118 

77.4 


82.-2 
53.8 
35.2 














1 

4 


i 

BT 

l 
3% 

l 
TB 

32 


171 
126 

87.8 
70.4 


85.7 
63.2 
43.9 
35.2 


50.1 
36.9 
25.6 
20.6 


328 
215 


164 
107 


74.5 
48.8 














3 

8 


1 

l 


156 
116 

79.7 


77.8 
57.8 
39.9 


45.4 
33.8 
23.3 


286 


143 


65.0 















344 



APPENDIX 



PRACTICAL TABLE OF 
CUTTING SPEEDS: STANDARD \" TOOL. 



Depth of 
Cut in 

Inches. 


Feed in 
Inches. 


Cutting Speed in Feet per Minute for a Tool which is to Last 1 Hour 
and 30 Minutes before Re-grinding. 


Soft Cast 
Iron. 


Medium 
Cast Iron. 


Hard Cast 
Iron, 


Soft Steel. 


Medium Steel. 


Hard Steel. 


_1_ 
16 


l 

64 

i 

32 

i 








510 
322 
203 


255 
161 

102 


116 
73.2 
46.2 




















3 

32 


i 

64 
1 
32 

1 

3 

32 

1 
8 


206 

147 
97.5 
76.0 
64.1 


103 
73.3 

48.8 
38.0 
32.1 


60.0 
42.8 
28.5 
22.2 
18.7 


445 
281 
177 
135 


223 

141 
88.7 
67.4 


101 
63.9 
40.2 
30.7 








1 

8 


1 

64 

1 
32 

1 
T6~ 

'A 

i 


194 

138 
93.1 
72.1 
41.8 


97.0 
69.3 
46.5 
36.1 
20.9 


56.7 
40.4 
27.2 
21.3 
12.2 


404 
255 
161 


202 

128 

81 


91.8 
57.9 
36.6 














3 
16 


64 

1 
32 

1 


182 

128 
86.1 
67.4 


91.0 
64.0 
43.1 
33.7 


53.0 
37.7 
25.1 
19.6 


359 
226 


179 
113 


81.6 
51.4 








1 
I 


1 
32 


173 
122 
81.9 


86.3 
61.0 
41.0 


50.4 
35.7 
23.9 


330 


165 


25.0 















INDEX 



Abrasion of cutting edge, 224 

tools subjected to, 211 
Absorbent glasses, in pyrometry, 169 
Absorption of power — see Power absorption 
Abutments, in composite tools, 268 
Accelerated production — see Maximum produc- 
tion, and Production 
Acceleration speed planers, 292 
Accuracy of pyrometers, 162, 169, 171 
Acetylene blow-pipe welding of tools, 184 
Air chucks — see Chucks 
Air hardening steels, discovery of, 13, 14 

see also High-speed steels 
Air quenching, 84, 97, 98 
Allowance for grinding, 76, 150 

machining, 190, 227 
shrinkage, etc., 180 
Alloy bath method of tempering, 123 
Alloy steels (see also Steels, High-speed steels, etc.), 
22 
cutting speeds on, 245 
Alpha iron, 33, 34, 38 
Aluminum, cutting speeds on, 245, 250 
in steel, 44 

lubrication in cutting, 233, 269 
milling of, 250, 269 
rake or front slope for cutters working 

on, 269 
table traverse in, 250 
Analysis of steel — see Steels, composition of 
Ancient steel making — see Steel, Manufacture of; 

Damascus; Crucible process, etc. 
Angles, cutting, in non-clearance tools, 257 

influence on cutting speeds and efficiency, 

235 
lip, influence on cutting speed, 235 
standard for tools, 255 
Annealed steel, constituents of, 25, 27 

stock, advantages in use of, 61, 65, 66, 129 
Annealing after forging, 76 

desirable in certain cases, 185 
discoloration of tool surface during, 132 
furnace, 129 

in remaking old tools, 185 
manganese steel, effect on, 39 
methods of, 61, 129, 133 
rapid, 130 

temperature range in, 131, 132 
time required, 130, 131, 132 
tungsten steels, 40 
Anthracite fuel in heating furnaces, 67 
"Anvil" principle in machine design, 279 
Apparatus — see Equipment 
Appendices, 330 



Appliances, need for adequate, 67, 122 

see also Equipment 
Arbor hole in rotary cutters, 269 
Armor plate, cutting speeds on, 250 

milling, 196, 250 
Austenite, 29, 35, 38 

fixing of, 39 
Austenitic condition, fixing, 35 

effect of heat treatment on, 42 
steels and red-hardness, 47 
Autogenous welding of high-speed tools, 183 
Automatic machine tools — see Machine tools 
Auxiliary drives, 288 

motors, use of, 285 



Back knives, composite (welded), 184 
rest, attachment of, 285 
slope in lathe tools, 257 
Band saws, high-speed steel, 201 
Barium chloride, 113 

process of hardening, 105 et seg. 
process of hardening, carbon steel 
tools, 117 
Bar stock, cutting, 185 
Barth slide rule, 236 
Bath hardening of tools, 107 
oil for quenching, 99 

operation of, in barium chloride process, 113 
quenching, 99 

tempering of tools, method of, 123 et seg. 
Bearings, proportions of, in high-speed machine 

tools, 283 
Belt drive, 286 

for auxiliary movements of machine 
tools, 288 
Bessemer converter, 10, 11 
steel, 9, 11 

method of manufacture, 10-11 
Beta iron, 33, 34, 38 
Billets, high-speed steel, 59 
"Black body" radiation, 171 
Blisters, formation of, on surface of tools, 119 
Blistering, prevention of, in heating tools, 92, 108 
Blades, inserted — ■ see Composite tools; Design of 

tools; and under various tools 
Bolometer, 158 

Boring operations, speeds in (see also Drilling), 247 
Brakes on machine tools, 289 
Brass cutting operations, 211, 233 

speeds and feeds in, 245, 

249, 250 
treatment of tools for, 
96, 128 



3'45 



346 



INDEX 



Brazing, in manufacture of composite tools (see 
also Composite tools; Compound tools, etc.). 
182, 183 

Breakage of tools, 140, 194, 199, 201, 298 
materials, minimizing of, 305 

Bristol pyrometer, 158, 162, 163, 164 

Brittleness ruinous in tools, 121 

Broaching operations, 205 

Bronze, high-speed tools for cutting, 211 

Brown platinum pyrometer, 158-159 

"Bubbles," formation of, on tool surfaces, 119 

"Burnt" skin, removal of, from tools, 149 



Calibration of pyrometers, 87, 162, 164, 170 
Capacity of machine tools, relation to powering, 289 
Carbon in steel, 23, 24, 32, 33 

steel, composition of, 23 

microscopic structure of, 26 
tools, hardening by barium chloride 
process, 117 
Carriage (lathe), attachment of, 282, 285 
Cast iron, cutting speeds on, 190, 244, 248, 249, 250 
efficiency of high-speed tools in cutting, 
190, 223 
Castings, allowance for machining, 228 
and heavy cutting, 190 
chilled, growing use of, 192 
Cast steel, 8 
Catalan forge, 3 
"Cementation" steels, 7 
Cementite, 27, 28, 38 
Chain drive for machine tools, 289 
Chatter, conditions making for, 153, 212, 226, 230, 
235, 252, 253, 254, 255, 267, 272 
effect on cutting speed, 230, 242, 325 
tool endurance, 212, 259 
Checks or cracks in tool surfaces, 136, 148, 152 
detecting, 185 
Chilled iron, machining, 192, 193, 241, 245 
Chipping castings, high-speed tools for, 207 
Chip, action of tool in cutting, 215, 224 
cooling of, 232 

development of heat in removing, 5 
distortion of, 218 
high-speed not unique, 234 
in drilling operations, 248 
production, variables a9ecting, 235, 242 
shape of, and tool efficiency, 254 
shearing of into sections, 220 
Chips, disposal of, 233, 292, 294 

nature and production of, 5, 6, 212, 235, 248, 
254, 258 
Chisels, high-speed, 207 
I H tempering, 128 

Chlorine fumes, in barium chloride bath operation, 

113, 119 
Chrome steel, cutting speeds on, 245 

for tool holders and tool bodies, 261, 
263, 272 
Chromium, cost of, 62 

influence in steel, 25, 39, 40, 44 
Chucks and other holding devices, design of, 308 
Cleaning tool surfaces, in barium chloride process, 

116 
Clearance angle, 256 



Clearance angle, influence on cutting speed, 235, 
242 
modification of, in certain cases, 
226 
in drills, 142, 273 

internal cutting tools, 247 
milling cutters, 142, 195, 268 
reamers, 271, 272 
of chips in aluminum cutting, 269 
tools without (non-clearance tools), 257 
Classification of jobs, 306 
Clutches, modification of, in reciprocating machines, 

298 
Coke furnace (see also Furnace), 66 
Colors, discrimination of, 93, 122, 124, 155 

relation to temperature, 65, 93, 122, 124, 
155, 156, 166 
"Cold end" in temperature maintenance, 163 . 
Compensator, use of, in pyrometry, 164 
Composite tools (see also under separate tools), 
183, 200, 209, 210, 262 
cost of, 195, 265, 317 
design of, 183 
dies, 203, 206 
lathe centers, 284 
method of securing cutters, 183, 

265, 266, 268 
reamers, 200, 271 
renewal of cutters or blades, 267 
rotary, 263 
saws, 202 
shears, 203 

wood working, 209, 210 
See also Compound tools; Tool 
holders; Welding; etc. 
Composition of steels — see Steels, composition of 
Constituents of steel, 25-38 
Conditions of maximum effect, 212 el seq. 

efficiency, variation in, 239 
Conservatism in use of high-speed steel, 64, 275, 303 
Consistency in temperature gages, 171 
Contour of cutting edges — see Design of tools; 

Chatter; etc. 
Cooling, in annealing, 130, 132 

changes caused in heated steel by, 30, 32 
comparative effect, in heated steel, of 

rapid and slow, 31-32 
cutting tools while at work, 232, 238 

effect on cutting speed, 241, 
249 
in grinding tools, 148, 151 
in hardening — see Hardening; Quench- 
ing; etc. 
Contour of cutting edge — see Design of tools; 

Chatter, Efficiency; etc. 
Cooperation in organization for maximum produc- 
tion, 321 
Coring and reaming compared with drilling, 190, 

197 
Cost of high-speed steel, 61-63 

constituents, 62 
tools, comparative, 195 
metal cutting and of metal removed, 338 
tool maintenance, 192 
tools, basis of, 190 

comparative, 327 



INDEX 



347 



Cost of tools, composite, 195, 265, 317 
lowered, 306 
reduction, 237, 300 
Cracks, formation of, 68, 69, 97 

detection of, 185 
Critical points, 29-36 

ascertaining, 177 

influence of manganese, nickel, 

chromium, etc., on, 39 
lag in cooling, 30 
range of, 41 
Cross rails, form of, 280 

section of tools, 252 
Crucible process, 55 

antiquity of, 3, 55 
development of, 8 
later methods, 8, 55 
manufacture of wootz, 3 
revived by Huntsman, 8 
steel, 3, 8 

among the ancients, 3-8 
preeminence of, 8 
See also Steel 
Cup wheels for tool grinding, 142 
Cut, depth of, 242 

allowable in malleable castings, 227 

effect on chatter, 226 

influence on efficiency and speed of 

tool, 235 
in castings with chilled surfaces, 304 
standardized, 238 
duration of, influence on cutting speed, 

235 
meter, Warner, 240 
Cutter heads for wood working machines, 209 
Cutters, inserted — see Composite tools; Tool hold- 
ers; Compound tools; Design of tools; 
etc. 
milling — see Milling cutters; Composite 
tools; etc. 
Cutting action, tearing away of chip, 215, 221 
angles, in internal cutting tools, 247 

influence on cutting speeds, 235, 242 
cost of and of metal removed, 338 
drills, influence on feed, 248 

in non-clearance tools, 257 
standard, 255 
See also Angles 
edge, abrasion of 

amount of curve, 255 
conduction of heat from, 262-263 
contour of, 242, 253 
not under heavy pressure, 221 
shape and angle of, influence on speed 
and efficiency, 235 
edges, brazed or welded — see Composite 
tools; Compound tools; etc. 
relation of number to life of the tool, 
269 
effect of high speed in, 6 
off dies, hot, 206 

stock from bars, 65 
operations, nature of, 215 et seq. 

pressure on tool in (see also 
Vibration; Chatter, Pressure 
oscillations; etc), 19 



Cutting operations, softening of tool in, 224 
support of tool in, 228 
speed, determining, 240 

effect on cost of production, 237 

tool, 6 
factors affecting, 235, 236, 240, 241 
high, when undesirable, 238 
in chilled iron cutting, 241, 245 
maximum limits, carbon steel tools, 6 

high-speed tools, 18 
relation to chattering, 227-228 
variables affecting, 235, 236, 240- 
241 
speeds and feeds, generalizations as to, 236 
table of, for drilling and 
like operations, 249 
case of short duration cuts, 306 
commercially practicable, 238, 292 
drills, etc., 197, 240, 248, 249 
in boring jobs, 247 
finishing jobs, 208 
milling nickel-chrome steel, 196 
milling operations, 250 
planer and shaper work, 194, 

250 
planer and shaper work, com- 
mercially practicable, 292 
roughing cuts, 245 
wood working operations, 209 
maximum, 241 j 
maximum with carbon steel tools, 

302 
on cast iron, 191, 244 
malleable castings, 245 
steel, 245 
phenomenal, 244 
reamers, 248-249 

relation of, in certain operations, 
247 
. table for determining, 334 
Taylor standard, 238, 339 
threading tools, 249-250 
with soft tools, 333 
time, diagram for ascertaining, 336 
tools, action of, 215 

factors in efficiency of, 226 
see also Tools, design of; Harden- 
ing; Tempering; Efficiency; An- 
nealing; Forging; Temperature; 
etc. 
transformation of energy in, 5 
Cylindrical furnace — see Furnace 

Damascus steel, 3, 4, 5, 8 
Dannemora iron, use in high-speed steel, 62 
Data, securing of, as basis for standard tempering 
temperatures, 127 
in temperature regulating, 175 
manufacture of high-speed 

tools, 178 
establishment of conditions 
for maximum production, 
235, 323 
Defects of early high-speed steels, 186 
Dead melting, in crucible process, 9, 58 
Depth of cut — see Cut 



348 



INDEX 



Design, end sought in, 212 

of furnaces — see Furnace 

machine tools, 212, 275 et seq. 

adjustments, 212, 285 
auxiliary motors, use of, 

285, 287 
bearings, 283 
brakes, 289 
distribution of material, 

279 
lathes, 279 et seq. 
milling machines, 286 
new requirements, -317 
planing machines, 286 
pulling and feeding power 
a factor in speeds and 
feeds, 242 
relation of powering to 

capacity, 
rigidity, 212 
solidity, 280 
speed changes, 287 
summary, 294 
torsional strains, 286 
variable-speed motors for 

•driving, 287 
weight essential, 280 
See also Machine tools 
tool rests, 285 
tools, 252, 319 

composite (inserted cutter), 265 
considerations affecting, 261 
continuity of structure desirable, 

182 
contour of cutting edge, 242 
dies, 274 

composite, 206 
drills, 141, 273 

factors affecting efficiency, 226 
milling cutter blades, 266-267 
milling cutters, 229, 263, 266-267 
clearance in, 195 
front slope in, 267, 

269 
helical, 266 
inserted cutter, 

195 
interlocking sec- 
tional, 270 
nicked cutting 

edges, 270 
overhang in 

blades, 268 
pitch in, 195, 268, 

269 
welded cutter 
blades, 184 
miscellaneous, 274 
overhang of inserted cutter blades, 

268 
rotary, 263 

threading taps and dies, 201 
Taylor on, 261 
wood working, 274 
Diameter of work, influence on cutting speed and 
efficiency, 235 



Dies, composite, 184, 203 

design of — see Design, above 
deterioration of, 204 
drawing, 206 
efficiency of, 203 
efficiency of blanking, 204 
embossing, 206 
forming, 206 
hardening of, 114, 118 

temperature for, 96-97 
heading, 206 
high-speed, 203 
hot cutting-off, 206 

forming and pressing, 206 
pneumatic tool, 207 
quenching or cooling, 100 
"sinking" of, 206 
snap, 207 
threading, breakage of, 201 

cutting the threads, 181 
design of, 201 
hardening of, 117-118 

temperature, 96 
prevention of rough surfaces and 

cutting edges, 181 
tempering, 127-128 
tongs for handling, 119 
Disc grinders, disadvantages of, in certain cases, 

146 
Discoloration in annealing, 132 
Discoveries, modern method of making, 20 
Dog, use of, in turning operations, 308 
Drawing temper — see Tempering 
Dressing grinding wheels, 138 

Drilling, compared with coring and reaming, 190, 
197 
punching, 197 
cooling or lubricating the drill, 233 
feeds and speeds in, 197, 244, 248 
machine for using high-speed drills with 
maximum efficiency, 277 
weak, 298 
remodeled, 295 
removal of chips, 233 
Drills, breakage of, 199, 248 
clearance in, 141, 273 
finish of the flutes, 273 
flat, use and efficiency of, 199 
grooved, 199 

multiple lip, efficiency of, 199 
peripheral speed of, 248 
splitting of, 273 
twist, design of, 273 
twisted, 273 

in plate drilling, 199 
welded shank, 184 

See also Design; Economy; Efficiency; Feeds 
and speeds; Grinding; Hardening; Tem- 
pering; etc. 
Drive, belt, 286 

electric, 286, 289 

for operating heavy tail stocks, 285 
in remodeled machines, 296 
of reciprocating machines, remodeling of, 
298 
Drives, auxiliary, 285, 288 



INDEX 



349 



Eccentricity in rotary cutters, relation to chatter, 

230 
Economies, effecting, 327 

elements affecting, 237 
table of, in a specific case, 328 
Edge tools — see Tools; Hardening; Grinding; 

Tempering; etc. 
Efficiency, comparative, of rotary and reciprocating 
cuts, 194 
contrasts, 302 

maximum, conditions of, 310 
measure of, 232 
relative, of grinders, 135 
tool, blanking dies, 203-204 

brass, bronze, German silver work- 
ing, etc., 211 
drills, finish of flutes and, 273 
flat, 199 

multiple-lipped, 199 
twist, 197-201 
twisted, 186, 274, 300 
factors affecting, 188, 197, 235, 252 
forming dies, 206 
high-speed tools in general, 20 
in cast iron cutting, 190, 223 
influence of shape in, 254 
machine tool equipment a factor in, 

276 
milling cutters, 194-195 
multiple-lipped drills, 199 
planer and shaper work, 194 
punches, 204 
reamers, 199 
relation to prime and maintenance 

cost, 192 
rock working, 211 
rotary compared with reciprocating, 

194 
successive grindings and, 76 
taps and dies, 201 
variables affecting, 188, 197, 235, 

252 
wood working, 210 
Egypt, early use of steel tools in, 1 
Electric drive — see Drive 
Electrical annealing, 133 

furnace, see Furnace 
hardening, methods of, 102 
method of steel manufacture, 12 
process of making high-speed steel, 55 
resistance pyrometer, 158, 164 
tempering, 126 

welding of compound or composite tools, 
183 
Elements in composition of steel, 23-25, 46-51, 330 
influence of, see 
Hardening 
Embossing dies, 206 

Energy, transformation of, in metal cutting oper- 
ations, 1 
Endurance limits of machine operator, 304, 310 
tools, 6 
of cutting tools, factors affecting, 212, 
226 

machine tools, 307 
Engineering, place of high-speed steel in, 186, 300 



Engineering, place of mushet steels in, 14 

works, production in, 279 
Equipment, barium chloride hardening process, 109 
forging, 66, 73, 87 
gas manufacturing, 81 
grinding, 141 

hardening, air quenching, 97 
furnaces, 78-86 
heat regulating (see also 

Pyrometry), 86 
oil quenching, 99 
supplemental, 87 
machine tool, policy of scrapping, 
295, 303 
remodeling old, 295- 

299 
tool efficiency and, 276, 
322 
manufacture of high-speed tools and 

adequate, 67, 78, 82 
quenching, air, 97 
oil, 99 
Excess metal, grinding from tools, 149 
Experiences, misleading, 64, 323 
Experimentation — see Tests 

Facility, securing, in machine tools, 212 

Factory organization and maximum production, 

217, 320 
Feed devices, positive, on drilling machines, 249 
drive, power absorbed in, 253 
effect on chattering, 226 
factors effecting, 242 
or traverse, pressure in case of non-clearance 

tools, 258 
stresses, 289 

table for determining, 334 
wood working operations, 209 
Feeds and speeds, drills, 197, 244, 248, 249 

gain in case of rotary tools, 194 
milling operations, 250, 268 
reamers and like tools, 249 
See also Speeds 
Ferrite, 27-30, 38 
Fery pyrometer — see Pyrometer 
"Fiddle" principle in machine design, 279 
File cutting chisels, hardening temperature for, 97 
File test, 180 
Files, high-speed, 201 
Finish grinding in toolmaking, 149 

in wood working operations, 209 
influence on efficiency of drills, 273 
Finishing chilled castings, 193 

cuts, effect of using poorly ground tools 
on, 230 
efficiency of high-speed tools, in, 

208 
speeds in, 250 
hardening temperature for, 96 
in manufacture of high speed steel bars, 

59 
tools, grinding of, 137 
Fire — see Forging; Hardening; etc. 
Fire end pyrometer, 159 

ends (pyrometer) , care and protection of, 
164-165 



350 



INDEX 



Fire ends (pyrometer), deterioration of, 162, 165 
Fish oil, for quenching bath, 100 
Fixtures, use of, in accelerated production, 212 
Fixing the state of steel, 33 
Flat drills — see Drills 
Flaws and cracks — see Cracks 
Flushing, in grinding, 136, 148, 151 
Forge, Catalan, 3 
gas, 66, 67 

shop, place of high-speed tools in, 206 
Forging, primitive, 1 

or machining tools, expediency of, 77 
the tools, 64 et seq. 

expedients in, 73 

fire for heating, 66, 68 

gages for use in, 73 

hammering, cautions as to, 70 

heating for, 68 

rough or close, expediency of, 

73 
successive steps in, 71 
temperature required, 69 
tungsten steels, difficulty of, 69, 71 
Forming cutters, hardening temperature, 96 
dies, 206 

knives for wood working, 209 
Formulas in metal cutting operations, 236 

theoretical, for high speed steel com- 
position, 45 
Foster ring turret lathe, 278 
Frames of machine tools, spring in, 298 
Front slope in milling cutters, 267-269 
Fuel for heating furnaces — see Furnaces 
Fumes, disposal of, 107 

from barium chloride bath, 113 
from lead bath, 107 
Furnace, annealing, 129 

barium chloride treatment, 109 

coke fired, 67, 78 

crucible, 86 

cylindrical, 86 

design of, 78, 82, 109, 130 

electrical, 111 

operation of, 113 
equipment for toolmaking plant, 84 
fuel to use, 67, 78, 80 
gas fired, 80 

convenience and economy of, 

67 
operation of, 111 
venting of, 111 
hardening, 78 

melting, in high speed steel manufac- 
ture, 55 
oil fired, 78 

muffle, use in steel making, 7 
oil fired, 78 
open hearth, 9 

temperature fluctuations in, 107 
tempering, 82, 122, 124 

Gages, forging limits, 73 

function in accelerated production, 315 
Gaging temperature — see Temperature 
Gamma iron, 33, 34, 38 
Gas, aa a furnace fuel, 80 



Gas, cost of, 81 

forge — see Furnace 
furnace — see Furnace 
kind to use in gas fired furnaces, 82 
plant for manufacture of, 81 
Gear cutters, 196 
Gears, in machine tools, 289 

strengthening of, in remodeling machines, 

297 
stripping of, in reciprocating machines, 298 
German silver, high-speed tools for working, 211 
Glazing of grinding wheels, 135 
Gladwin, Mr. Henry, improves method of air 

hardening, 14 
Gledhill, Mr. J. M., on cooling tools, 102 
Graphite, free, in steel, 27, 29 
Grinding, nature of the operation, 136 
of tools, 134 et seq. 

allowance for, in size of tool, 

76, i50 
amount of material removed, 

152 
automatic or hand, 140 
checking of surfaces in, 148 
cup wheel, advantages of in, 

142, 146 
design of machines for, 138 
direction the wheel should run, 

150 
disc wheels, disadvantages of, in 

certain cases, 146 
drills, 137, 148 
dry or wet, 148 
edge tools, 137 
equipment for, 141 
face or land (back), 152, 267 
finishing tools, 137 
frequency of, 152, 230, 303 

and lip slope, 257 

relation to cutting 

speeds, 235, 241 

hot tools, 76, 149 

importance of proper, 134 

improper, and effect on finish 

cuts, 230 
inaccurate, and chatter of tool, 

230 
increase of efficiency with suc- 
cessive grindings, 76, 149 
ntervals between (see also 

frequency, above), 303 
jigs or fixtures for, 142, 145 
off excess metal, 76, 149 
organization for, 322 
positive feed in, 146 
prior to hardening, 76, 92, 148 
proper, a factor in efficiency, 237 
rotary tools, 230 
ruin of tools in, 135, 136 
stone to use, 134 
V-shaped periphery, advantages 

of, in certain cases, 147 
wheel to use, 134, 148 
wheels, dressing of, 138 
glazing of, 135 
kind of, to use, 134, 148 



INDEX 



351 



Grinding wheels, "loading" of, 135 

running speed of, 138 
truing of, 138 

"Guttering" of tools, 222 

Hack saws, high-speed, 201 

Hadfield steel, use of, in chilled roll finishing, 193 
Hammer, power, advantages of, in forging, 70 
Hammering high speed steel bars, 61 
Hammering, in forging, 70 
Hammers, high-speed, 207 
Hand tools, high-speed, 200 

Handling tools in the barium chloride process, 118 
heating, 96 

special tongs for, 97 
Hardening, barium chloride process, 105 et seq. 
bath for heating, use of, 107 
carbon steel tools by barium chloride 

or other bath process, 117 
dies, 118 

difficulty of, in case of certain tools, 265 
drills, method when using oven fur- 
nace, 96 
quenching or cooling of, 100 
temperature for, 96 
vertical furnace for, 83 
edge tools, temperatures, 96 
effect of tongs on, 94 
electrical, 102 
elements, 62 

cost of, 62 

influence of the several, in 
steel, 32, 39-45 
essentials of the method, 101 

Taylor-White method, 
101 
Fred W. Taylor on, 332 
heating — see Heating, below; also 

Temperature regulation, etc. 
influence of carbon on, 32 

chromium on, 39, 44 
manganese on, 39-44 
molybdenum, aluminum, 

and tantalum on, 44 
nickel on, 39 
sulphur and phosphorus 

on, 45 
titanium, uranium, and 

vanadium on, 43 
tungsten on, 40-45 
lead bath method, 107 
martensite produced in, 35 
method of heating, 93-96 

ordinary, 13 
mushet steels, 13, 14 
plant, arrangement of, 87 

equipment for, 84 
pre-heating the tools in, 92 
superheating, effect of, 16 
temperatures — see Temperature 
theory of, 25-35, 38 
water cooling, 51, 53, 97 
See also Heating; Quenching; Temper- 
ature; etc. 
Hardness, extreme, not essential in high-speed 
tools, 121, 180 



Hardness, of material, relation to cutting speed, 
257 
tool, effect on cutting speed, 240 
red-, — see Red-hardness 
test, 180 
Hartness, Mr. James, on non-clearance tools, 257 
type of tools — see Non-clearance tools 
Head, lathe, design of, 281 
Heading dies, 206 
Heat, development of, in metal cutting, 6, 182 

dissipation of, at the cutting edge, 232, 257, 

262-264 
regulation of — see Temperature regula- 
tion 
treatment of high-speed steel, theory of, 42 
manganese steel, 39 
steel, effect of, 29 
Heating, difficulties of, in ordinary furnace, 107 

duration and extent of, in annealing, 131 
barium chlo- 
ride process, 
114 
forging, 68 
hardening, 91 
tempering, 125 
effect of rapid and of slow, compared, 31 

uneven, in forging, 68 
for annealing, 130-133 
forging, 68 

hardening, 91, 113-116 
tempering, 122-126 
gradual, necessary in forging, 66, 68 
handling of tools while, 96, 118 
in lead bath, 107 
method of, in hardening, 93, 96 
of tool during grinding, 136 
slender tools, 

uniformity in barium chloride process, 
107-108 
Heavy cutting, high-speed tools and, 187 
on castings, 190 
or close forging, 188, 190 
preeminence of high-speed tools in, 

188 
when desirable, 188 
Helical milling cutters, 266 
High-heat treatment, 15, 20 

and red-hardness, 47 
see also Barium chloride 
process; Hardening; Heat- 
ing; Taylor-White pro- 
cess; etc. 
High-speed cutting, power absorbed in, 194 
razors, 19, 208 
steel, adaptability of, 211 

analysis or composition of, 25, 

46, 47, 48, 330 
brands or makes, 17 

selection of, 319 
characteristic properties of, 47 
composition of — see analysis, 

above 
constituents of, 62 
cost of, 62-63 
defects of early, 17, 186 
development of, 17, 20 



352 



INDEX 



High-speed steel, especial field for, 187, 303 

heat-treatment of (see also Heat- 
ing; High-heat treatment; etc.), 
42 
influence of the ingredients (see 

also Hardening), 32-45 
limitations of, 211 
manufacture of, 55-63 
marvels of, 18 
"new," "superior," "improved," 

etc., 51-53 
place of, in engineering, 186 
range of utility, 186 et seq. , 
reason for high cost, 61 
recent developments in, 51-53 
relation to mushet steel, 46 
stinted use of, 64, 275 
theoretical formulas for, 45 
■wood- working tools, 18, 209-210 
tools — see Tools 
when undesirable, 238 
Holborn-Kurlbaum pyrometer, 158, 167 
Holding tools in machines, 285 
Hood for forge fire, 66, 91, 130 
Hoskins pyrometer, 158, 162, 163 
Hot-forming and pressing dies, 206 
Hot grinding of tools, 149 
Howe, Professor, theory of steel hardening, 38 
Huntsman, revives crucible process, 8 

Ice bobbin, use of, in pyrometry, 164 

Identification of tools, 76 

"Improved" high-speed steels, 51-53 

Industrial revolutions, manner of accomplishment, 
19, 300 

Indication of temperatures, distant (see also Tem- 
perature), 160, 169, 173, 175 

Ingot molds, in manufacture of high-speed steel, 59 

Ingots, topping of, 62 

Ingredients of high-speed steel, influence of the 
several, 32-45 

Inserted-cutter tools — see Composite tools; Tool 
holders; etc. 

Inspection, careful, a factor in effecting econo- 
mies, 237 

Interlocking milling cutters, 270 

"Intermediate" steels, nature and composition of, 
50-53 
need and utility of, 49 

Internal cutting, speeds in, 247 

Iron, alpha, beta, gamma, and magnetic, 33, 34, 38 

Jigs and fixtures, use of, 212, 278 

design of, in accelerated production, 308 

for tool grinding, 142, 145 

use of, a factor in accelerated production, 237 

See also Chucks 
Jobs, changing over to use of high-speed tools, 323 
classification or standardization of, 306, 328 

Kerosene for quenching, in hardening, 100 
"Killing "or "dead melting" in crucible steel manu- 
facture, 58 
Knives, high-speed steel, 209 

wood-working, 18, 109-210 



Labor, an important factor in tool efficiency, 252 
Lag, in annealing, 172 

conversion of steel constituents, 30 
cooling as compared with heating critical 

range, 30 
pyrometers, 164, 171 
Land grinding, on rotary tools, 142, 152, 267 
Lathe beds, form of, 279, 281 
centers, design of, 284 
continuous head and bed, 283 
design — see Machine tool design 
heads or stocks, 281 
Lo-Swing type, 281 
primitive, 2 
ring-turret, 278 
stocks, adjustability of, 281 

tail, 284 
tools — see Tools 
Lead bath, difficulties in use of, 107 

uses of, 94 
Lead, in twist drills, 273 
Le Chatelier pyrometer — see Pyrometer 
Length or duration of cut, effect on cutting speed, 

241 
"Letting down" martensite, 37 

or tempering, 121 
Life of tool — see Tool; Grinding; Endurance; etc. 
Limitations of high-speed steel, 211 

tools, 187, 207 
Limits gages, in forging, 73 

of pyrometer ranges, 158 
Line shafting, power absorbed by, 287, 289 
Lip angle, influence on cutting speed, 235 

surface, pitting, guttering, or wearing of, in 
metal cutting, 223-224 
pressure upon, in cutting, 217 et seq. 
"Loading" of grinder wheels, 135 
Lo-Swing lathe, 281 
Low-heat treatment and tempering, 122 

in the Taylor-White method of 

hardening, 102 
superfluous?, 102 
Lubricant or cooling agent, effect of, on cutting 

speeds, 235, 241, 249 
Lubrication in cutting aluminum, 269 

remodeled machines, 296 
of cutting tools, 232 
machine tools, 283 

Machine operator — see Workman 

tool equipment a factor in tool efficiency, 

276 
tools, adjustments in, 285 

automatic, and high-speed thread- 
ing tools, 201 
place of, 304-305, 310 
tool lubrication, 232 
brakes on, 289 
design — see Design 
endurance of, 307 
new types, 276 

requirements, 317 et seq. 
pulling and feeding power, influence 

on possible speeds, 242 
reciprocating, limitations of, 290 
relation of powering to capacity, 289 



INDEX 



353 



Machine tools, remodeling of, 295-299, 307, 317, 324 
rigidity in, 212 
scrapping of, 
single purpose, 278 
superseding of, 308, 317 
speed changes in, 287 
tool efficiency and adequate equip- 
ment, 188 
torsional strains in, 286 
use of, with high-speed tools, 298 
types, inadequacy of old, 19 
Machinery, influence on development of steels, 5 
Machining, allowance for, in manufacturing, 227 

tools from stock compared with forging, 

129 
unannealed high-speed steel, 61 
compared with forging and finish ma- 
chining, in rapid production, 66, 77 
Magnetic chucks or jigs, use of, in rapid production, 
308 
property of steel, effect of heat on, 29 
Maintenance cost of machines, 307 
Malleable castings, allowance for machining of, 227 
broaching of, 205 
iron, cutting speeds and feeds on, 245, 
249-250 
Manganese and red-hardness, 44 

effect on hardening, 39 
influence and importance of, in high- 
speed steel, 13, 23, 44 
steel, effect of annealing, 39 
heat treatment of, 39 
unsuitable for cutting tools, 39 
use in chilled roll turning, 193 
Manganese-bessemer steel, 13 
Manufacture of high-speed steel, 55 et seq. 

tools ■ — see High-speed 
tools 
steel, later methods, 7-12 

primitive methods, 1-5 
Marble working, 211 
Marking of tools, 76 
Martensite, 33 

in high-speed steel, 42 
nature of, 38 

produced in the hardening process, 35 
Material, character of, influence on cutting speeds, 
250 
handling and storage of, 312 

of, a factor in rapid production, 
237 
in process, routing of, 322 

reduction of scrap in, 306 
non-uniformity of, 303 
refractory, cutting of, 303, 323 
transportation and storage of, 312, 318 
Maximum effect, conditions of, 212 et seq. 

production, conditions of, 239, 304, 310 
factory organization and, 

317 
intelligent supervision and, 

317, 318 
wage system and, 321 
See also Production 
Melting high-speed steel, methods of, 56, 58 
point of high-speed steel, 96 



Mesure and Nouel pyrometer — see Pyrometer 
Metal cutting, ancient methods, 2 
cost of, 338 
development of, 5, 14 
limitations of tools, 14 
nature and theory of, 215-228 
pressure oscillations in — chatter, 

226 ' 
problems involved, 226 
nature of the variables in, 240 
tearing action in chip formation, 221 
quality of, effect on cutting speed, 240 
working, ancient, 2 
Method, scientific, and industry, 178 
Methods — see under the various processes 
Milling and planing compared, 194 

cutters, allowance for shrinkage, 181 
clearance required, 195 

in aluminum 
cutting, 269 
composite (see also Composite 

tools), 263 
design of — see Design 
efficiency of (see also Efficiency), 

194-196, 208 
front slope in, 267 
grinding of, 137, 141, 142, 148 
hardening temperatures, 96 
heating for hardening, 93 
helical, 266 
inserted teeth (see also Composite 

tools), 195 
interlocking, 270 
nicked edges, 270 
number of teeth, 195, 268, 269 
peripheral speeds. 250 
"riding" of, 244 
shape of cutting teeth, 266 
tempering, 127 
feeds in, 247, 250, 268 
in finishing operations, 208 
refractory materials, 196 
speed or feed increase?, 194 
speeds in, 247, 250 
traverse in, 244 
Motor drive — see Drive 
Motors for auxiliary drives, 285, 288 

variable speed, in machine driving, 287 
Molybdenum, cost of, 62 

influence in high-speed steel, 44 
Morse thermo gage, 158, 167 
Muffle furnace, use of, 7 
Muffles, use in oil-fired furnaces, 78 
Multiple tools, use of, in rapid reduction, 198, 200, 

246 
Mushet, improves the crucible process, 8 

develops self-hardening or mushet steel, 

13, 24 
steel, character and composition of, 23, 
40, 46 
discovery of, 13 

effect of high-heat treatment on, 15 
introduction of, 8, 14 
place in engineering 
relation to high-speed steel, 46 
tungsten and chromium in, 40 



354 



INDEX 



" New" high-speed steels, 51-53 

hardening of — see Hard- 
ening 
quenching in water, 53, 

97 
tempering, 121 
Nicholson experiments, 213, 220, 221, 253 
Nickel, influence in high-speed steel, 44 
effect on hardening, 39 
steel, 39 

cutting speeds on, 245, 250 
use for tool holders, etc., 263 
Nickel-chrome steel, milling of, 196 

thermo-couple, 161 
Nicking of milling cutter teeth, 270 

or stamping tools, 76, 185 
Nomenclature of steels, 22 
Non-clearance cutting tools, 216, 242, 257, 259, 

286, 287 
Non-cutting operations, high-speed tools for, 203 
Non-metal working operations, high-speed tools in, 

209 
Non-uniformity of material and use of high-speed 

tools, 303 
Nozzles, in wet grinding, 148 

Odors, suppression of, in oil quenching bath, 100 
Oil as a cooling agent in grinding, 148 
fired furnace — see Furnace 
quenching in (see also Quenching), 79-100 
tempering furnace, 124 

operation of, 125 
Open hearth steel, manufacture of, 9 
Operator, machine — see Workman 
Optical pyrometry (see also Pyrometer), 158, 165, 

166, 169 
Ores, primitive methods of extracting, 1 
Organization of shop and maximum production, 
310 
tool room — see Tool room; and 
Tool supply 
problem of, 300 
Overhang of tools, 228, 229 

relation to number of grindings, 
267 
Overload, provision for, in powering of machine 

tools, 297 
Oxidation, air quenching and, 99, 114 
cause of, 95 

in the heating furnace, 68, 80 
of the lead bath, 108 
prevention of, in annealing, 130-132 

barium chloride pro- 
cess, 105, 108, 114 
hardening, 94, 105-106 

Pack-hardening, 94 
Paper cutting knives, high-speed, 209 
Paraffine oil as a lubricant in cutting operations, 
233, 269 
aluminum cutting, 
269 
Pearlite, 27 

conversion of, 29 
nature of, 38 
Performances of carbon steel tools, 6 



Performances of high-speed tools, 18, 52 

% "new" high-speed steels, 52 

see also Efficiency 
Peripheral speeds, drills, 248 

milling cutters, 250 

table and method 
for determin- 
ing, 334 
Personal equation in temperature determination, 

93, 124, 156, 171 
Phosphorus, effect of, in steel, 23 

influence in high-speed steel, 45 
Photometric pyrometer, 158, 166 
"Pickling," in the manufacture of high-speed steel, 

62 
Pitch, in cutters working on aluminum, 269 

milling cutters, 268 
"Pitting," of surface of tools in hardening, 119 

(wearing) of cutting lip of tool, 223, 224 
Planer tool, compound, 183 
tools, 194 

breakage of, 194 
(wood), knives, 209 
Planers, accelerated speed, 292 

see also Reciprocating tools 
Planing compared with rotary cutting, 194 
cutting speed in, 194, 250 
efficiencies in, 194 

machine design (see also Design of ma- 
chine tools), 286 
Platinum-rhodium thermo-couple, 161 
Pneumatic tools, dies for, 207 

hardening temperatures, 97 
"Poker" pyrometer, 159 
Power absorbed by line shafting, 287, 289 
machine tools, 287 
old types of machines, 303 
in feed drive, 253 

rapid cutting, 194, 286 
available, a factor in cutting speeds, 244 
required, a factor in the use of high-speed 

tools, 307 
transmission of, 289 
Powering, ample, a requisite in high-speed ma- 
chines, 278 
in remodeled machines, 296 
of machine tools, 286 

provision for over- 
loads, 297 
relation to capacity, 
289 
Pre-grinding, wheel for use in, 148 
Pre-heating furnace, 79, 92 

in the barium chloride process, 115, 116 
tool hardening, 92, 115, 116 
Premium system of wage payment and the use of 

high-speed tools, 310 
Press dies, 206 

working operations, 206 
Pressure, air and gas in gas-furnace operation, 82, 
111 
feed, in case of non-clearance tools, 258 
on lip of tool, influence on cutting speed 
and efficiency, 236 
tool in cutting operations, 19 

non-clearance cutting tools, 258 



INDEX 



355 



Pressure on tool, influence of, 238 

oscillations in metal cutting, 214, 219, 
220, 226 
on cutting toojs, 254 
Primitive tools and methods of making them, 1 
Prismatic pyrometer, 158, 166 
Problem of organization, 300 

Problems in the use of high-speed tools — see High- 
speed tools 
unintelligent attacking of, 64 
Production, accelerated, methods of securing (see 
also Maximum production), 323 
maximum — see Maximum produc- 
tion 
psychology and physiology of, intensi- 
fied, 304 
"Pulling" the crucible, 56 
Punches, high-speed, 203 
design of, 274 
efficiency of, 204 
forging or machining of, 77 
hardening temperatures, 96 
tempering of, 128 
Punching operations, 204 

replaced by drilling, 197 
Pyramids, tools used in construction of, 1 
Pyrometer, adaptation to purpose, 157 

attention to, in heating operations, 93 
Bristol thermo-couple, 158, 162-164 
Brown platinum, 158-159 
electrical resistance, 158, 164 
expansion, 158, 159 
Fery absorption, 158, 166 

radiation, 86, 158, 169-171 
Holborn-Kurlbaum, 158, 167 
Hoskins thermo-couple, 158, 162, 163 
in hardening, 86 
lag in, 164, 171 

Le Chatelier electrical resistance, 165 
optical, 158, 166 
thermo-couple, 158-161 
manipulation of, 165 
Mesure and Nouel, 158, 166 
optical, 158, 165 et seq. 
photometric, 158, 166 
power of discrimination, 162-171 
prismatic, 158, 166 
radiation, 158, 169, 170 
resistance, 158, 164 
selection of, 173 
"sentinel," 87, 157, 158 
thermo-couple, 158 et seq. 
Uehling, 158, 165 
use of, 115 
Wanner, 158, 166 
water current, 158, 159, 165 
Pyrometers, accuracy of, 162, 167, 169, 171 
calibration of, 87, 162, 164, 170 
checking for accuracy, 87 
conspectus of, 158 
deterioration of, 87, 162, 165, 169 
discrimination of, 162, 164, 166, 167, 

169, 171 
limits of ranges, 158, 161 
responsiveness of, 164, 171 
Pyrometry, 155 et seq. 



Pyrometry, optical, 165 el seq. 

recent developments in, 163 

- Quality of material, effect on cutting speed, 235, 
240, 241 
Quenching agents, 97 

air, apparatus for, 84 

cautions as to, 100 

methods, 97, 114, 116 

methods in connection with barium 

chloride process, 114, 116 
oil, apparatus for, 99 
kind of oil to use, 99 
methods of, 99 
slender tools, 100 
special methods, 102 
water, 53, 97 
Quivering, in metal cutting (see also Vibration; and 
Chatter), 213 

Radiation, black body, 171 

pyrometer — see Pyrometer' 
Rake, in case of internal cutting tools, 247 
milling cutters, 267-269 
lack of, in reamers, 249 
Range of utility of high-speed steel, 186 et seq. 
Ranges of pyrometers, 158, 161 
Rapid production — see Maximum production 
reduction, use of multiple tools in, 246 
steels (same as high-speed steels), 13 
Razors, high-speed, 19, 208 
Reamers, adjustable or expansion, 271, 272 
clearance and relief in, 272 
design of, 270 
efficiency of, 199 
floating, 

grinding of, 142, 145, 148 
hand, 201 

inserted cutter (see also Design of tools; 
Composite tools; Compound tools; 
etc.), 200, 271 
nature of work of, 272 
quenching of, 100 
speeds and feeds for, 248, 249 
tempering of, 127 
wear of, 199 
welded blade, 184 
Reaming, coring, and displaced by drilling, 190, 197 
Re-annealing tools, 76 
Recalescence — see Critical points 
Recarburizing, in Bessemer process, 11 
Reciprocating machines, breakage of tools in, 194 
high-speed tools and, 193 
limitations of, 290 
remodeling drives of, 298 
rotary cutting and, 194, 

212, 292 
stripping of gears in, 298 
tendency away from use 
of, 212 
Records, temperature, forms of, 76, 177 

tool making, 178 
Red-hardness, 41, 42, 47, 121 

manganese and, 44 

production of, in high-speed steel, 332 

range of, Frontispiece, 41 



356 



INDEX 



Red-shortness, 23 
Reduplication of tools, 179 

Refinement of method in the manufacture of high- 
speed steel, 61 
Refinement of method in the manufacture of high- 
speed tools, 78 
Refractory materials, high-speed tools and, 303, 323 

milling of, 196 
Re-grinding — ■ see Grinding 
Regulation of temperature — see Temperature 

regulation 
Relation of tool and work, 212 
Relief in reamers, 272 
Re-making worn tools, 185 

Remodeling of machine tools — see Machine tools 
Repair of broken tools — welding, 184 
Repetitive work, production of, 277 
Resistance pyrometer — see Pyrometer 
Responsiveness of pyrometers — see Pyrometers 
Reversion, austenite to pearlite, 31, 33 
Revolutions per minute, table for determining, 334 
"Riding" of tool against flank of work, 258 

tools, 226, 244, 247 
Rigidity in machine tools, 212, 279 
tool holders, 262 

rests, 285 
securing in remodeling of machines, 298 
Ring turret lathe, 278 
Riveting dies, 207 

Rock drilling, high-speed steel in, 211 
Rolling high speed steel bars, 61 
Rose reamers — see Reamers 
Rotating tools, composite — see Design of tools 
Rotary cutting compared with reciprocating cuts 

(see also Reciprocating machines), 194 
Rough forging and heavy grinding compared with 
close forging, 73 
surfaces, prevention of, on certain tools, 181 
Roughing cuts, speeds in, 245 

tools, tempering of, 127 
Routing of pieces in process, 322 
Run, length of, a factor in cutting speed, 241 
Running speed of grinding wheels, 138 
time, standard, 230 

Sandstone wheels for tool grinding, 148 
Sawing high-speed steel, 65, 185 

operations, 201 
Saws, grinding of, 144 
high-speed, 202 
inserted tooth, 265, 267 
"Scaling," causes of, 95 

see also Oxidation 
Scrapping of machine tools (see also Machine tools), 
207, 295, 303, 304, 308 
material in process, minimizing of, 
303, 304, 306, 327 
Screw machine tools, hardening and tempering of, 96 
Self-hardening steels — see Mushet steel 
Self-sharpening of tools (see also Non-clearance 

tools), 215, 216 
Self-treatment (low-heat) of high-speed tools, 102 
Semi-high-speed steels, 49, 50 
Sentinel pyrometer, 87, 157 
Separating stock from bar, 65, 185 
Shank, strength of, in reamers and similar tools, 271 



Shanks of twisted drills, 274 

Shape of iool, influence on cutting speed and effi- 
ciency, 235, 253 
Shaper operations, cutting speeds in, 250 

tools, 194 
Sharp tools, advantages in using, 152 
Sharp-angle tools, Hartness type, 216, 242, 257, 287 
Shaving, high-speed, 19, 208 

Shaving or chip, nature and formation of, 215 et seq. 
Shear blades, composite or compound, 184, 203 
hardening temperature, 96 
tempering of, 128 
steel, 7 
Shearing action in chip formation, 218 et seq. 
nature of, 219 

operations, use of high-speed tools in, 203 
Shears, design of, 274 

high-speed, 203 
Shop organization — ■ see Organization 
Shrinkage, in hardening, allowance for, 181 

minimizing in barium chloride process, 
117 
Side slope in lathe tools, 257 
Silicon, function of, in steel manufacture, 45 

influence in steel, 23, 45 
Size, allowance for loss in grinding, etc., 180 
Slender tools — see Tools 
Slide rule, Barth, 236-237 

Slide rule, use of, in solution of rapid production 
problems, 310 
standardizing cutting opera- 
tions, 236 
Slotter and similar tools (see also Reciprocating 

machines), 194 
Slotting, use of saws for, 202 
Smelting, prehistoric, 1 

Smoothness of tool surface, securing, 181, 182 
Snap dies, 207 

hardening temperature, 97 
tempering, 128 
Sodium carbonate (soda ash), 113 
Soft metals, cutting of, 211 

rake for milling cutter teeth, 

in cutting, 269 
speeds on, 245 
Softening of tool edges in metal cutting, 224 
Solidity in machine tools, 212, 279, 280 
"Special" high-speed steels, 50 
Special tools, use of, in preference to standard, 261 
Speed, accelerated, in planing machines, 292 

changes in machine tools, 278, 287, 290 

remodeled machines, 296 
gains in newer types of reciprocating ma- 
chines, 194 
meter, use of, 239 
tables, Taylor standard, 339 

too fast?, 239 
Speeds, cutting — see Cutting speeds 
Spindles, in remodeled machines, 298 

use of hollow, 283 
Splitting of drills, 273 
Sponge iron, 3 

Stamping or nicking tools, 76, 185 
Standard running time, 230 

tools (see also Tools), 255 
Taylor, 259 



INDEX 



357 



Standardization of tools (see also Tool design; and 

Tool supply), 238 et seq. 
Standardizing depth of cut, 238 

jobs, 328 
Steel, bessemer, 9-11 
blister, 7 
carbon, 23 

composition of, 24 
microscopic structure of, 26 
cast, 8 

cementation, 7 

composition of — see Steels, below 
constituents of, 25-38 
crucible, 3, 8 

early manufacture and use of, 3-4 
revival of method of manufacture, 8 
cutting speeds in drilling, 249 
milling, 250 
on, 244, 245 
Damascus, 3, 4, 8 
definition of, 22 
development of, 7, 13 
double or double shear, 7 
electric, 12 

fixing the several states, 33 
for universal use, 47 
high-speed — see High-speed steel 
"intermediate," 49 

influence of the several ingredients, 32-45 
manganese-bessemer, 13 

manufacture, discovery and development of 
methods, 1 el seq. 
methods of modern, 8 et seq. 
modern science of, 7 
primitive methods of, 1-4 
production of uniform qual- 
ity, 5 
mushet — see Mushet steel 
nickel, 23 
non-tungsten, 51 
open hearth, 9 

prevention of defects in, 23 • 
properties of, 22, 40 
theory of hardening, 25 et seq. 
tungsten (see also High-speed steel; Mushet 
steel; etc.), 13, 23 
Steels, air-hardening, 13 
alloy, 22 
ancient, defects of, 5 

remarkable properties of, 5 
similarity to modern steels, 7 
composition of carbon, 23, 24 

high-speed or air-hardenfng, 

25, 46, 330 
"intermediate," "semi-high- 
speed," "special," etc., 
50, 330 
mushet or self-hardening, 23, 
24, 46 
variations in, 24 - 
microscopic structure of, 26 et seq. 
nomenclature of, 22 
rapid (same as high-speed), 13 
self-hardening — see Mushet steel 
semi-high-speed, 49 
"special," 49 



Steels, variations in quality of primitive, 5 

water hardening, 22, 51, 53, 97 
Steady rest, use of, 242 
. Stiffness of tool, influence of, on cutting speed, 236 
Stock, heavy, recommended forhigh-speed tools, 252 

separating from the bar, 65, 185 
Stocks, lathe, 281, 284 
Stone cutting, high-speed tools for, 211 

to use in tool grinding, 134 
Stop watch, use of, in standardizing jobs, 239 
Storage, auxiliary (materials in process) , relation to 
rapid production, 312 
of materials a factor in rapid production, 
237 
Strains, effects of, 93 

guarding against, in tool making, 76 
internal, development of, in tools, 61, 65, 

68, 93, 97, 118, 125 
torsional, in machine tools, 286 
Strength of structural forms, relative, 279 
Stresses, feeding or traverse, 289 

on high-speed tools, 19, 252 

tool, in sharp-angle tools, 259 
lip slope and, 257 
relation of cutting angle to, 256 
Structural forms, relative strength of, 279 
Sulphur, effect of, in steel, 23 

in high-speed steel, 45 
"Superior" high-speed steels, 51 
Super-heat treatment (see also High-heat treat- 
ment), 15 
Supervision, intelligent, and effective use of high- 
speed tools, 310, 317, 318, 320 
Swedish iron, 28 

in high-speed steel, 62 

Table traverse — see Traverse 

Tantalum, nature of, and influence in high-speed 

steel, 44 
Taps and dies, threading, breakage of, 201 

cutting speed of, 249, 250 
cutting the threads, 181 
design of, 201 
efficiency of, 201 
hardening by the barium 
chloride 
process, 117, 
118 
temperature, 
96 
prevention of rough sur- 
face on, 189 
tempering of, 127 
Taylor, Fred W., develops the high-heat treatment 
for tungsten steels, 20 
doctrine of re-grinding tools, 303 
experiments with mushet steels, 15 
formulas for metal cutting opera- 
tions, 236 
on the hardening of high-speed 

tools, 101, 332 
standard cutting speeds, 238, 339 

tools, 242, 255, 259 
" The Art of Cutting Metals," In- 
troduction, 332 
Taylor-White method of hardening, 101, 332 



358 



INDEX 



Taylor-White process as a factor in the develop- 
ment of tool steels, 8 
development of, 14 
essentials of, 101 
the high-heat treatment, 15, 
101 
Tearing action in chip production, 221 
Teeming, in the manufacture of high-speed steel, 

58-59 
Teeth, number of, in milling cutters, 195, 268, 269 
Temper colors, 37 

Temperature and color, relations of, 93, 124, 155, 
156, 166 
annealing range, 131, 132 
"cold end," maintenance of, 163, 164 
cones ("sentinel pyrometer"), 87, 157 
control in barium chloride process, 107 
determination, 155 

colors and, 93, 124, 

155, 156, 166 
eye and, 93, 124, 155 
personal equation in, 

171 
see also Temperature 
indication, below 
effects of, unsuitable, 61 
fluctuations in barium chloride bath, 
115 
oven and other fur- 
naces, 107 
forging, 69 

gages, adaptation to purpose, 157 
conspectus of, 158 
need for, 86 
ranges of, 158 
see also Pyrometer 
hardening, limits of, 93, 96 

in pre-heating, 116 
range of, Frontispiece, 15, 

41 
regulation of, 86, 93, 174 
permissible variations in, 

97 
summary of, 96 
see also under particular 
tools 
indication, distant, 160, 169, 173, 175 
measurement, uncertainty of, 124 
range in red-hardness, Frontispiece, 
41 
hardening, Frontispiece, 15, 41, 
93, 96, 97 
records, form of, 176, 177 
reduplication of, 169 
regulation in barium chloride process, 
113-115 
coke furnace, 68 
system of, 86, 174 
value of data, 175 
rolling or "finishing" high speed steel 

bars, 61 
tempering, 127 

range in, 121, 122 
Tempering, 121 

a heat treatment, 29 
alloy bath method, 123 



Tempering and the low-heat treatment, 122 
electrical, 126 
furnaces, 122 

importance of data and method, 127 
in oil, 38, 124 
nature of process, 37 
oil required, 126 
purpose of, 35 

range of temperatures, 15, 37, 127 
temperatures, summary of, 127 
the."new" high-speed steels, 121 
time required for, 123, 125 
See also under particular tools 
Test record form, 324 
Tests, the making of, 319 
Thermo-couple pyrometer, 158, 159, 169 

pyrometry, recent developments 
in, 163 
Thermometer, mercurial, where used, 157 
Threading tools — see Taps and dies 
Time-labor, a factor in efficiency, 252 
Time necessary in annealing, 61, 130, 131, 132 
of cutting, when relatively short, 238 
required for cutting, diagram for determin- 
ing, 336 
tempering, 123, 125 
Tire turning, 213, 300 
Titanium, cost of, 62 

influence in steel, 43 
Tool base, need for true, 76 
truing of, 76, 228 
cost — see Cost of tools 
efficiency — see Efficiency 
holder stock, use of, 61, 65, 182, 261 
holders, design of, 261, 262 

limitations and use of, 182, 262 
holding, 285 

position, modification of, in remodeling ma- 
chines, 299 
pressure on, in cutting (see also Stresses), 

19, 252 
problem, 322 

quality of, effect on cutting speed, 241 
relation to work, 212 
rests, design of, 285 

room, organization of, 152, 312, 315, 317 
sections, special, 253 

standard, 252-253 
self-sharpening of (see also Non-clearance 

tools), 215, 216 
steel, cutting speeds and feeds in drilling, 249 
supply and maintenance, 315 
support, in cutting operations, 228 
tests, 319 
Tools, breakage of, 140, 194, 199, 201, 298 

brazed and welded (see also Composite tools; 

and Compound tools), 182 
broad-nosed, tendency- to chatter, 255 
chilled roll turning, 245 
compound (see also Compound tools; Com- 
posite tools; and under particular tools), 
182, 263 
composite — see Compound tools; Compos- 
ite tools; Welding; Tool holders; etc, 
design of — see Design of tools 
deterioration of blanking dies, 204 



INDEX 



359 



Tools, displacement of old, by high-speed, 317 
dulling of, 152 
earliest, 1 

effect of using dull, 152 
efficiency — see Efficiency; and under par- 
ticular tools 
endurance limits of, 6 
forging of, 64 

form, relation to chattering, 226 
grinding system, 315, 322 
"guttering" of, 222-223 

handling of, in barium chloride process, 118 
Hartness non-clearance — see Non-clearance 

tools 
high-speed, beginning'the use of, 319 

comparative cost of, 20, 195 
conditions affecting efficiency, 

188 
conservatism in the use of, 303 
considerations affecting the use 

of, 306 
cost of — see Cost of tools 
economy in the use of, 300 
efficiency (see also under partic- 
ular tools), 20 
on cast iron, 190 
especial field for, 187, 303 
hand, 200 
handling of, 308 
heavy cutting and, 188 
limitations of, 187, 207 
manufacture of, especial care re- 
quired in, 67 
or purchase of, 64, 
134, 155, 308, 
309, 317, 318, 
322 
position in industrial engineer- 
ing, 300 
problems affecting the use of, 

315 
reciprocating machines and, 193 
relative economy of, 186 
inserted cutter — see Composite tools ; and 

under particular tools 
keeping sharp, 151 
lathe, broad-nosed, 254 

compound high-speed-carbon, 183 
grinding of, 142 

Hartness non-clearance (see also Non- 
clearance tools), 257 
Taylor standard, 242, 255, 259 
tempering of, 127 
maintenance, 322 

cost, 192 
manufacture or purchase of, 64,134, 155, 308, 

317, 318, 322 
multiple, use of, in rapid production, 245 
nicking or marking, 76 
non-clearance — see Non-clearance tools 
planer, 194 

progressive dulling of, 152 
purchase or manufacture of, 64, 134, 155, 

308, 317, 318, 322 
reduplication of, 179 
repair of broken, 184 



Tools, "riding" of, in cutting operations, 226 

self-sharpening — see Non-clearance tools 

shaper, 194 

sharp, advantage in the use of, 152 

sharp angle, use of (see also Non-clearance 

.tools), 286 
Blotter, 194 
standard, 255 

standardization of, 238, 315 
supplying to workmen, 312 
Taylor standard, 242 
threading — see Taps and dies 
"warming up" of, 
wear of, 199, 223, 224, 227 
worn, remaking of, 185 
Toledo steel, 3, 5 

Tongs, special forms of, 87, 94, 118, 119 
Topping ingots, 62 

Torsional strains in machine tools, 279, 286 
Toughness, restoration of, in hardened tools, 121 
Transportation of material in process — see Ma- 
terial 
Traverse, factors affecting, 242 

in milling aluminum, 250 
operations, 250 
or feed, table for determining, 334 
Troostite in high-speed steel, 43 

nature of, 38 
Truing grinding wheels, 138 

tool bases — see Tool bases 
"Try outs," 324, 328 
Tungsten a fixing agent, 41 

and self-hardening steels, 40 
cost of, 62 

effect of, on hardening, 40 
influence in high-speed steel, 44 
steels, effect of tempering on, 41 
properties of, 13 
Turning locomotive tires, 213, 300 
Turret lathe, Foster ring, 278 
Twist and twisted drills — see Drills 
Type metal for anchoring inserted cutter blades, 267 

Uehling pyrometer, 158, 165 
Unannealed stock, use of, 261 
Uniformity in tools, securing, 78 

lack of, in material, effect on standard 
speeds, 241 
Universal adaptation of high-speed steel, 211 
Uranium, influence in steel, 43 
Utility of high-speed steel, range of, 186 et seq. 
Universal use, high-speed steel for, 47 

Vanadium, cost of, 62 

influence in steel, 43 
Variables affecting efficiency, 235 

in metal cutting, nature of, 240 
Venting of gas furnaces, 111 
Ventilation of hardening plant, 88 
Vibration and chatter, 226 

elimination of , in machine tools, 278, 280 
in metal cutting, causes and nature of, 

213, 214 
lateral, 214 

in Hartness tools, 258 
minimizing, 215, 285 



360 INDEX 

Wage system, relation to efficient use of high-speed Wheel, kind to use in tool grinding, 134, 137, 
tools, 310 142 

maximum production, 321 Wire drawing, dies for, 206 

Wanner pyrometer, 158, 166 Wolfram — see Tungsten 

" Warming up" of tools in cutting operations, 102 Wood working, high-speed tools in, 209 
Warner cut meter, 240 operations, finish obtained with 

Water as a quenching or cooling agent, 53, 97 high-speed tools, 209 

current pyrometer, 158, 159, 165 tools, design of, 274 

hardening high-speed steels, 51, 53 efficiency of, 210 

Wear of cutting tools, 199, 223, 224, 227 tempering, 128 

reamers, and like tools, 199 Wootz, 3 

Web of twist drill, design of, 273 Work and tool, relation between, 212 

Weight essential in high-speed machine tools, 280 Workman, the, a factor in rapid production, 317, 
Welded (compound) tools, 183, 263 321 

shear blades and dies, attitude toward high-speed tools, 

203 310 

utility of, 184 consideration for, in accelerated 

Welding high-speed steel to carbon steel, 182, 184 production, 310 

in repairing broken tools, 184 endurance limit of, 304, 310, 317 

lathe beds and head stocks, 282 training in the proper use of high- 

Wet or dry grinding of tools, 136, 148 speed tools, 310 

Whale oil for the quenching bath, 100 Worn tools, re-making of, 185 






siAY 3 1940 



LIBRARY OF CONGRESS 




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